An empirical phenomenological investigation of procrastinating behaviour
- Authors: Barratt, Neal Anthony
- Date: 2010
- Subjects: Procrastination Self-actualization (Psychology) Cognitive psychology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2929 , http://hdl.handle.net/10962/d1002438
- Description: A qualitative empirical phenomenological study was undertaken to determine the self-experience of procrastinating behaviour. Five students each gave an account of an occasion when they procrastinated. The resultant protocols were analysed and the Situated Structure of each individual’s experience was reported. From these, the General Structure of procrastinating behaviour was determined. A further, novel step was added to the standard methodology, whereby ‘themes’ were extracted from participant protocols and a ‘Composite Reality’ of everyday-life procrastination was rendered. Participants’ accounts suggest they are concerned the results of intellectual tasks they undertake will be seen as equivalent to their quality of being-as-an-individual: poor work results will be interpreted by important-others as evidence of participants’ poor quality of self – which is to be avoided. This study suggests that procrastination is a ploy used by individuals to avoid criticism, by deflecting assessment of their capacity to complete a task well, to instead, what they are capable of when only a limited time is available. Conclusions drawn by the important-others of participants’ true ability are thereby confounded. The results achieved in the phenomenological study were compared with others originating from various quantitative studies, and considerable overlap was found. The experiential richness of the phenomenological results point to a worthwhile methodological strategy for future procrastination research.
- Full Text:
- Date Issued: 2010
- Authors: Barratt, Neal Anthony
- Date: 2010
- Subjects: Procrastination Self-actualization (Psychology) Cognitive psychology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2929 , http://hdl.handle.net/10962/d1002438
- Description: A qualitative empirical phenomenological study was undertaken to determine the self-experience of procrastinating behaviour. Five students each gave an account of an occasion when they procrastinated. The resultant protocols were analysed and the Situated Structure of each individual’s experience was reported. From these, the General Structure of procrastinating behaviour was determined. A further, novel step was added to the standard methodology, whereby ‘themes’ were extracted from participant protocols and a ‘Composite Reality’ of everyday-life procrastination was rendered. Participants’ accounts suggest they are concerned the results of intellectual tasks they undertake will be seen as equivalent to their quality of being-as-an-individual: poor work results will be interpreted by important-others as evidence of participants’ poor quality of self – which is to be avoided. This study suggests that procrastination is a ploy used by individuals to avoid criticism, by deflecting assessment of their capacity to complete a task well, to instead, what they are capable of when only a limited time is available. Conclusions drawn by the important-others of participants’ true ability are thereby confounded. The results achieved in the phenomenological study were compared with others originating from various quantitative studies, and considerable overlap was found. The experiential richness of the phenomenological results point to a worthwhile methodological strategy for future procrastination research.
- Full Text:
- Date Issued: 2010
A study of intra-African relations an analysis of the factors informing the foreign policy of Malawi towards Zimbabwe
- Authors: Njoloma, Eugenio
- Date: 2010
- Subjects: Malawi -- Foreign relations -- Zimbabwe Zimbabwe -- Foreign relations -- Malawi Malawi -- Politics and government -- 20th century Malawi -- Politics and government -- 21st century Southern African Development Community
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2818 , http://hdl.handle.net/10962/d1003028
- Description: There has been only limited scholarly analysis of Malawi’s foreign policy since its independence in 1964 with key texts focusing primarily on the early years of the new state. Perhaps due to its relatively small stature – economically, politically and militarily – in the region, very little attention has been paid to the factors informing Malawi’s apparently uncritical foreign policy response to the Zimbabwe crisis since it began in the late 1990s. This thesis addresses this deficit by locating its understanding of Malawi’s contemporary foreign policy towards Zimbabwe in the broader historical and contemporary context of bilateral relations between the two states and the multilateral forum of SADCC and SADC. It is argued that the Malawi’s long-standing quest for socio-economic development has forced it to manoeuvre a pragmatic but sometimes contentious foreign policy path. This was also evident until the end of the Cold War and the concomitant demise of apartheid in South Africa in the early 1990s. Malawi forged deliberate diplomatic and economic relations with the region’s white-ruled Zimbabwe (then Southern Rhodesia) and South Africa in pursuit of its national economic interests while the majority of southern African states collectively sought the liberation of the region by facilitating the independence of Zimbabwe and countering South Africa’s apartheid and regional destabilization policies. In the contemporary era, there has been a convergence of foreign policy ambitions in the region and Malawi now coordinates its regional foreign policy within the framework of SADC, which itself prioritizes the attainment of socio-economic development. However, to understand Malawi’s response to the Zimbabwe crisis only in the context of SADC’s “quiet diplomacy” mediation efforts obscures important historically rooted socioeconomic and political factors that have informed relations between Malawi and Zimbabwe and which cannot, it is argued, be ignored if a holistic understanding of Malawi’s position is to be sought. This study argues that the nature of historical ties between Malawi and Zimbabwe and the role of Malawi’s leaders in driving its long-standing quest for socioeconomic development have not only informed its overall foreign policy behaviour in the region but underpin its contemporary relations with Zimbabwe.
- Full Text:
- Date Issued: 2010
- Authors: Njoloma, Eugenio
- Date: 2010
- Subjects: Malawi -- Foreign relations -- Zimbabwe Zimbabwe -- Foreign relations -- Malawi Malawi -- Politics and government -- 20th century Malawi -- Politics and government -- 21st century Southern African Development Community
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2818 , http://hdl.handle.net/10962/d1003028
- Description: There has been only limited scholarly analysis of Malawi’s foreign policy since its independence in 1964 with key texts focusing primarily on the early years of the new state. Perhaps due to its relatively small stature – economically, politically and militarily – in the region, very little attention has been paid to the factors informing Malawi’s apparently uncritical foreign policy response to the Zimbabwe crisis since it began in the late 1990s. This thesis addresses this deficit by locating its understanding of Malawi’s contemporary foreign policy towards Zimbabwe in the broader historical and contemporary context of bilateral relations between the two states and the multilateral forum of SADCC and SADC. It is argued that the Malawi’s long-standing quest for socio-economic development has forced it to manoeuvre a pragmatic but sometimes contentious foreign policy path. This was also evident until the end of the Cold War and the concomitant demise of apartheid in South Africa in the early 1990s. Malawi forged deliberate diplomatic and economic relations with the region’s white-ruled Zimbabwe (then Southern Rhodesia) and South Africa in pursuit of its national economic interests while the majority of southern African states collectively sought the liberation of the region by facilitating the independence of Zimbabwe and countering South Africa’s apartheid and regional destabilization policies. In the contemporary era, there has been a convergence of foreign policy ambitions in the region and Malawi now coordinates its regional foreign policy within the framework of SADC, which itself prioritizes the attainment of socio-economic development. However, to understand Malawi’s response to the Zimbabwe crisis only in the context of SADC’s “quiet diplomacy” mediation efforts obscures important historically rooted socioeconomic and political factors that have informed relations between Malawi and Zimbabwe and which cannot, it is argued, be ignored if a holistic understanding of Malawi’s position is to be sought. This study argues that the nature of historical ties between Malawi and Zimbabwe and the role of Malawi’s leaders in driving its long-standing quest for socioeconomic development have not only informed its overall foreign policy behaviour in the region but underpin its contemporary relations with Zimbabwe.
- Full Text:
- Date Issued: 2010
Induced plant responses of different Lantana camara L. (Verbenaceae) varieties to herbivory by Falconia intermedia (distant) (Hemiptera: Miridae)
- Heshula, Unathi-Nkosi Lelethu Peter
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2010
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Lantana camara -- Biological control -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Weeds -- Biological control -- South Africa -- Eastern Cape , Invasive plants -- Biological control -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5911 , http://hdl.handle.net/10962/d1015368
- Description: A highly variable invasive shrub, Lantana camara L. (Verbenaceae), has been notoriously difficult to control thus far despite a well established biological control programme in South Africa. A promising leaf-feeding biological control agent, Falconia intermedia (Distant) (Hemiptera: Miridae), released to control this invasive plant eventually crashed at three out of five sites in the Eastern Cape Province. In the Mpumalanga Province, after initially colonising and building up high numbers on the L. camara stands the agent populations crashed. Several reasons for these population crashes have been suggested, but induced plant defences have not been investigated. Although plants face the challenge of herbivory by various organisms while remaining immobile, some plants may possess the ability to induce physical and/or chemical defensive responses following feeding and thus prevent further plant tissue damage and loss. Laboratory trials were conducted to determine the existence, nature and effect of physical and chemical feeding-induced responses of L. camara on the performance of the leaf-feeding biological control agent, F. intermedia. Lantana camara plants used in the study were obtained from five localities in the Eastern Cape Province, South Africa, while the insect culture was established from field populations. Plants from all varieties on which F. intermedia was released significantly increased the toughness of their leaves compared to control treatment plants. In addition, plants from three localities: Lyndhurst Farm, East London and Port Alfred, significantly increased trichome density after prolonged feeding by F. intermedia. On the three varieties showing increases in these two factors (i.e. leaf toughness and trichome density), oviposition, survival and feeding damage by the mirid agent was significantly lower on previously damaged plants. A significant negative correlation between trichome density and population numbers was found (R²= 0.52, p < 0.0003), suggesting that an increase in trichome density strongly contributes to a reduction in F. intermedia's growth. The growth and reproduction of the resistant plants was not significantly impacted by F. intermedia feeding. The defensive responses were found to be plant systemic and rapidly induced as they were elicited and expressed throughout the plant in both damaged and undamaged leaves within five weeks after insect release. Leaf toughness and trichome density were not significantly increased after feeding on plants from Whitney Farm and Heather Glen Farm. On the contrary, mirid individuals performed significantly better on plants from Whitney Farm and Heather Glen Farm than on plants of other varieties, indicating their susceptibility and suitability to the agent and the lack of induced resistance against the agent. Plants from all localities besides East London showed some level of tolerance and overcompensated for feeding damage by increasing plant growth and reproductive factors on plants fed upon. This was however only significant in two variables of the more susceptible localities, Whitney Farm and Heather Glen Farm. This increase in plant fitness did however indicate an induced defence response by these plants to feeding, a response designed to lessen the effects of agent feeding. Headspace volatile analysis was used to investigate any volatile chemical responses by L. camara due to F. intermedia feeding at two of the five localities chosen: East London and Whitney Farm. There was no significant difference in headspace volatiles emitted by leaves of plants from the East London insect infested and control treatment plants. On the Whitney Farm damaged plants however there was a 2.5 fold increase in the emission intensity of one of the three main compounds, later identified as Beta-caryophyllene. Three major chemical constituents which were found to be common to leaf volatiles of the two varieties were identified through gas chromatography-mass spectrometry (GC-MS) from the damaged and undamaged leaves of these two varieties. The methods used in collecting leaf volatiles were shown to be significant in the strength of chromatogram peaks. Using general authentication methods and purified standards, one of these was identified as the sesquiterpene, Beta-caryophyllene (C₁₅H₂₄). This compound is one of the major constituents found in isolations of L. camara varieties worldwide. This is the first such work done on a variety of L. camara in South Africa, and hopefully the beginning of more in-depth studies of the volatile organic chemicals from the numerous naturalised varieties of L. camara. It is suggested that the sum of these responses may play a role bigger than is currently understood in this plant-insect relationship. It is also argued that feeding induced plant defences may play an important role in attempts to control alien plants using insect agents.
- Full Text:
- Date Issued: 2010
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2010
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Lantana camara -- Biological control -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Weeds -- Biological control -- South Africa -- Eastern Cape , Invasive plants -- Biological control -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5911 , http://hdl.handle.net/10962/d1015368
- Description: A highly variable invasive shrub, Lantana camara L. (Verbenaceae), has been notoriously difficult to control thus far despite a well established biological control programme in South Africa. A promising leaf-feeding biological control agent, Falconia intermedia (Distant) (Hemiptera: Miridae), released to control this invasive plant eventually crashed at three out of five sites in the Eastern Cape Province. In the Mpumalanga Province, after initially colonising and building up high numbers on the L. camara stands the agent populations crashed. Several reasons for these population crashes have been suggested, but induced plant defences have not been investigated. Although plants face the challenge of herbivory by various organisms while remaining immobile, some plants may possess the ability to induce physical and/or chemical defensive responses following feeding and thus prevent further plant tissue damage and loss. Laboratory trials were conducted to determine the existence, nature and effect of physical and chemical feeding-induced responses of L. camara on the performance of the leaf-feeding biological control agent, F. intermedia. Lantana camara plants used in the study were obtained from five localities in the Eastern Cape Province, South Africa, while the insect culture was established from field populations. Plants from all varieties on which F. intermedia was released significantly increased the toughness of their leaves compared to control treatment plants. In addition, plants from three localities: Lyndhurst Farm, East London and Port Alfred, significantly increased trichome density after prolonged feeding by F. intermedia. On the three varieties showing increases in these two factors (i.e. leaf toughness and trichome density), oviposition, survival and feeding damage by the mirid agent was significantly lower on previously damaged plants. A significant negative correlation between trichome density and population numbers was found (R²= 0.52, p < 0.0003), suggesting that an increase in trichome density strongly contributes to a reduction in F. intermedia's growth. The growth and reproduction of the resistant plants was not significantly impacted by F. intermedia feeding. The defensive responses were found to be plant systemic and rapidly induced as they were elicited and expressed throughout the plant in both damaged and undamaged leaves within five weeks after insect release. Leaf toughness and trichome density were not significantly increased after feeding on plants from Whitney Farm and Heather Glen Farm. On the contrary, mirid individuals performed significantly better on plants from Whitney Farm and Heather Glen Farm than on plants of other varieties, indicating their susceptibility and suitability to the agent and the lack of induced resistance against the agent. Plants from all localities besides East London showed some level of tolerance and overcompensated for feeding damage by increasing plant growth and reproductive factors on plants fed upon. This was however only significant in two variables of the more susceptible localities, Whitney Farm and Heather Glen Farm. This increase in plant fitness did however indicate an induced defence response by these plants to feeding, a response designed to lessen the effects of agent feeding. Headspace volatile analysis was used to investigate any volatile chemical responses by L. camara due to F. intermedia feeding at two of the five localities chosen: East London and Whitney Farm. There was no significant difference in headspace volatiles emitted by leaves of plants from the East London insect infested and control treatment plants. On the Whitney Farm damaged plants however there was a 2.5 fold increase in the emission intensity of one of the three main compounds, later identified as Beta-caryophyllene. Three major chemical constituents which were found to be common to leaf volatiles of the two varieties were identified through gas chromatography-mass spectrometry (GC-MS) from the damaged and undamaged leaves of these two varieties. The methods used in collecting leaf volatiles were shown to be significant in the strength of chromatogram peaks. Using general authentication methods and purified standards, one of these was identified as the sesquiterpene, Beta-caryophyllene (C₁₅H₂₄). This compound is one of the major constituents found in isolations of L. camara varieties worldwide. This is the first such work done on a variety of L. camara in South Africa, and hopefully the beginning of more in-depth studies of the volatile organic chemicals from the numerous naturalised varieties of L. camara. It is suggested that the sum of these responses may play a role bigger than is currently understood in this plant-insect relationship. It is also argued that feeding induced plant defences may play an important role in attempts to control alien plants using insect agents.
- Full Text:
- Date Issued: 2010
Developing a systematic model for the capturing and use of African oral poetry: the Bongani Sitole experience
- Authors: Mostert, Andre
- Date: 2010
- Subjects: Sitole, Bongani, 1937- Communication and culture Oral tradition in literature Oral tradition -- Africa Ethnoscience -- Africa Folk poetry, African
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3579 , http://hdl.handle.net/10962/d1002154
- Description: Oral traditions and oral literature have long contributed to human communication. The advent of arguably the most important technology, the written word, altered human ability to create and develop. However, this development for all its potential and scope created one of the most insidious dichotomies. As the written word developed so too the oral word became devalued and pushed to the fringes of societal development. One of the unfortunate outcomes has been a focus on the nomenclatures associated with orality and oral tradition, which although of importance, has skewed where the focus could and should have been located, namely, how to support and maintain the oral word and its innate value to human society in the face of what has become rampant technological developments. It is now ironic that technology is creating a fecund environment for a rebirth of orality. The study aims to mobilize technauriture as a paradigm in order to further embed orality and oral traditions to coherently embrace this changing technological environment. The central tenet of the study is that in order to enhance the status of orality the innate value embodied in indigenous knowledge systems must be recognized. Using the work of Bongani Sitole, an oral poet, as a backdrop the study will demonstrate a basic model that can act as a foundation for the effective integration of orality into contemporary structures. This is based on work that I published in the Journal of African Contemporary Studies (2009). Given the obvious multi-disciplinary nature of the material the work covers a wide cross section of the debate, from questions of epistemology and knowledge in general in terms of oral traditions, through the consciousness and technical landscapes, via the experience with Sitole’s material to issues of copyright and ownership. This work has also been submitted for publication together with my supervisor as a co-author. The study intends to consolidate the technauriture debate and lay a solid foundation to support further study.
- Full Text:
- Date Issued: 2010
- Authors: Mostert, Andre
- Date: 2010
- Subjects: Sitole, Bongani, 1937- Communication and culture Oral tradition in literature Oral tradition -- Africa Ethnoscience -- Africa Folk poetry, African
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3579 , http://hdl.handle.net/10962/d1002154
- Description: Oral traditions and oral literature have long contributed to human communication. The advent of arguably the most important technology, the written word, altered human ability to create and develop. However, this development for all its potential and scope created one of the most insidious dichotomies. As the written word developed so too the oral word became devalued and pushed to the fringes of societal development. One of the unfortunate outcomes has been a focus on the nomenclatures associated with orality and oral tradition, which although of importance, has skewed where the focus could and should have been located, namely, how to support and maintain the oral word and its innate value to human society in the face of what has become rampant technological developments. It is now ironic that technology is creating a fecund environment for a rebirth of orality. The study aims to mobilize technauriture as a paradigm in order to further embed orality and oral traditions to coherently embrace this changing technological environment. The central tenet of the study is that in order to enhance the status of orality the innate value embodied in indigenous knowledge systems must be recognized. Using the work of Bongani Sitole, an oral poet, as a backdrop the study will demonstrate a basic model that can act as a foundation for the effective integration of orality into contemporary structures. This is based on work that I published in the Journal of African Contemporary Studies (2009). Given the obvious multi-disciplinary nature of the material the work covers a wide cross section of the debate, from questions of epistemology and knowledge in general in terms of oral traditions, through the consciousness and technical landscapes, via the experience with Sitole’s material to issues of copyright and ownership. This work has also been submitted for publication together with my supervisor as a co-author. The study intends to consolidate the technauriture debate and lay a solid foundation to support further study.
- Full Text:
- Date Issued: 2010
An investigation into what influences action competence-oriented teaching and learning processes in a school environmental club
- Authors: James, Alison
- Date: 2010
- Subjects: Environmental education -- South Africa -- East London Environmental education -- Activity programs -- South Africa -- East London Environmental literacy -- South Africa -- East London Environmental literacy -- Study and teaching -- South Africa -- East London Active learning -- South Africa -- East London Competency-based education -- South Africa -- East London Teacher-student relationships -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1619 , http://hdl.handle.net/10962/d1003501
- Description: This interpretive case study sought to determine what influenced action competence-oriented teaching and learning processes in a high school environmental club. The goals were to describe a year of activities, within the TALON environmental club at Hudson Park High School in East London, South Africa and to identify how pedagogical, contextual and relational factors influenced action competence processes amongst club members. I explored how action competence theory and praxis have helped in other school education settings with the aim of establishing better environmental practices. The IVAC model of pedagogy (Jensen & Schnack, 1997) was used as a framework to operationalise action competence processes within the TALON Club. This entailed carefully examining investigative, visioning, action and change processes unfolding through the four themes of the club: plants, animal welfare, waste issues and our community outreach programme at Bongulethu High School. Using questionnaires, interviews, observation and a journal as the main methods of data collection I was able to make five analytical statements that related to the influence of pedagogy, the influence of context and the influence of relational dynamics within the TALON Club. The pedagogical processes were affected by the TALON members wanting to avoid any activities that were ‘too much like school’. However this served to compromise the action and visioning phases within the club, resulting in superficial and poorly-informed action-taking. The influence of context served to both enable and constrain action competence processes. The club and school structures therefore shaped the form that fledgling actions took as the TALON members participated in the meetings and outings and fulfilling the traditional expectations of the school community. Relational dynamics and a desire for fun took precedence over the action competence processes. Although the Club members were motivated by a sense of moral responsibility they were unable to articulate this concept into the club activities. In addition there were the power gradients between the educators and members to consider as determinants of the extent of participatory, democratic interactions. This complex interplay of factors influenced the action competence processes in the club. Recommendations were made on how best to work with the concepts of participation and democracy towards improving the reflexivity and knowledge base of both the educators and learners. In this way action competence processes will be better supported within the club in future.
- Full Text:
- Date Issued: 2010
- Authors: James, Alison
- Date: 2010
- Subjects: Environmental education -- South Africa -- East London Environmental education -- Activity programs -- South Africa -- East London Environmental literacy -- South Africa -- East London Environmental literacy -- Study and teaching -- South Africa -- East London Active learning -- South Africa -- East London Competency-based education -- South Africa -- East London Teacher-student relationships -- South Africa -- East London
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1619 , http://hdl.handle.net/10962/d1003501
- Description: This interpretive case study sought to determine what influenced action competence-oriented teaching and learning processes in a high school environmental club. The goals were to describe a year of activities, within the TALON environmental club at Hudson Park High School in East London, South Africa and to identify how pedagogical, contextual and relational factors influenced action competence processes amongst club members. I explored how action competence theory and praxis have helped in other school education settings with the aim of establishing better environmental practices. The IVAC model of pedagogy (Jensen & Schnack, 1997) was used as a framework to operationalise action competence processes within the TALON Club. This entailed carefully examining investigative, visioning, action and change processes unfolding through the four themes of the club: plants, animal welfare, waste issues and our community outreach programme at Bongulethu High School. Using questionnaires, interviews, observation and a journal as the main methods of data collection I was able to make five analytical statements that related to the influence of pedagogy, the influence of context and the influence of relational dynamics within the TALON Club. The pedagogical processes were affected by the TALON members wanting to avoid any activities that were ‘too much like school’. However this served to compromise the action and visioning phases within the club, resulting in superficial and poorly-informed action-taking. The influence of context served to both enable and constrain action competence processes. The club and school structures therefore shaped the form that fledgling actions took as the TALON members participated in the meetings and outings and fulfilling the traditional expectations of the school community. Relational dynamics and a desire for fun took precedence over the action competence processes. Although the Club members were motivated by a sense of moral responsibility they were unable to articulate this concept into the club activities. In addition there were the power gradients between the educators and members to consider as determinants of the extent of participatory, democratic interactions. This complex interplay of factors influenced the action competence processes in the club. Recommendations were made on how best to work with the concepts of participation and democracy towards improving the reflexivity and knowledge base of both the educators and learners. In this way action competence processes will be better supported within the club in future.
- Full Text:
- Date Issued: 2010
The migration of the term "civil war" : a social constructivist explanation
- Authors: Bailie, Lawrence Craig
- Date: 2010
- Subjects: Civil Wars United States -- History -- Civil War, 1861-1865 Iraq -- History -- Civil War, 1991
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2845 , http://hdl.handle.net/10962/d1006022 , DOI http://doi.org/10.21504/10962/d1006022
- Description: Although the occurrence of wars between states has been in decline, the same cannot be said of conflict within states – especially when considering the innumerable ‘Civil Wars’ said to have occurred since the end of the Cold War. In this context the use of the word ‘innumerable’ is qualified more by the variance in how ‘Civil War’ is understood as a concept (leading to different claims as to how many conflicts of this kind may have occurred over a period of time) and less by their large number. Claims regarding the occurrence of ‘Civil War’ suggest this type of conflict to be the dominant form at least since the end of World War Two. This prevalence in the face of a decline in inter-state warfare has afforded greater interest to ‘Civil War’ as a topic of inquiry. The understanding that ‘Civil Wars’ have with time increased in their occurrence and changed in their nature comes under investigation in this thesis and is seen as problematic in that the means by which a phenomenon is measured (i.e. through its nature) must be fixed so as to measure the frequency of that phenomenon. Using Social Constructivism as a theoretical lens of inquiry, sense is made of this understanding and, furthermore, the true meaning behind the claim that ‘Civil War’ has changed is revealed. The empirical evidence that accompanies this theoretical work exists in the American Civil War of 1861–1865 and the debate over the conflict in Iraq following the U.S. invasion in 2003. This debate is used as a means by which to bring the contestation over the notion of ‘Civil War’ to the fore, while a comparison of this conflict with the quintessential American Civil War reveals the migration of the term.
- Full Text:
- Date Issued: 2010
- Authors: Bailie, Lawrence Craig
- Date: 2010
- Subjects: Civil Wars United States -- History -- Civil War, 1861-1865 Iraq -- History -- Civil War, 1991
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2845 , http://hdl.handle.net/10962/d1006022 , DOI http://doi.org/10.21504/10962/d1006022
- Description: Although the occurrence of wars between states has been in decline, the same cannot be said of conflict within states – especially when considering the innumerable ‘Civil Wars’ said to have occurred since the end of the Cold War. In this context the use of the word ‘innumerable’ is qualified more by the variance in how ‘Civil War’ is understood as a concept (leading to different claims as to how many conflicts of this kind may have occurred over a period of time) and less by their large number. Claims regarding the occurrence of ‘Civil War’ suggest this type of conflict to be the dominant form at least since the end of World War Two. This prevalence in the face of a decline in inter-state warfare has afforded greater interest to ‘Civil War’ as a topic of inquiry. The understanding that ‘Civil Wars’ have with time increased in their occurrence and changed in their nature comes under investigation in this thesis and is seen as problematic in that the means by which a phenomenon is measured (i.e. through its nature) must be fixed so as to measure the frequency of that phenomenon. Using Social Constructivism as a theoretical lens of inquiry, sense is made of this understanding and, furthermore, the true meaning behind the claim that ‘Civil War’ has changed is revealed. The empirical evidence that accompanies this theoretical work exists in the American Civil War of 1861–1865 and the debate over the conflict in Iraq following the U.S. invasion in 2003. This debate is used as a means by which to bring the contestation over the notion of ‘Civil War’ to the fore, while a comparison of this conflict with the quintessential American Civil War reveals the migration of the term.
- Full Text:
- Date Issued: 2010
The biology of austroglanis gilli and austroglanis barnardi (siluriformes : austroglanididae) in the Olifants River system, South Africa
- Authors: Mthombeni, Vusi Gedla
- Date: 2010
- Subjects: Catfishes -- South Africa -- Olifants River , Fishes -- South Africa -- Olifants River -- Growth , Freshwater fishes -- Effect of pesticides on -- South Africa -- Olifants River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5370 , http://hdl.handle.net/10962/d1015222
- Description: Austroglanis gilli and A. barnardi are endemic to the Clanwilliam-Olifants System in the Western Cape, South Africa. The populations of each of these species are considered to be threatened by various anthropogenic activities, which include inappropriate agricultural practice and impacts of alien invasive fish species. The purpose of this thesis was to assess the life-history of these two endangered species in order to contribute to understanding their biology. Such information is vital for the development of strategies for their conservation. Marginal zone and marginal increment analyses from sectioned lapilliar otoliths of both A. gilli and A. barnardi showed a unimodal peak, suggesting a single annulus formation. The oldest specimens of A. gilli and A. barnardi were 12+ and 14+ years, respectively. The growth of A. gilli and A. barnardi was relatively slow and was best described by the von Bertalanffy growth curve as: L, = 131.56(1 - exp(- 0.27(t - 1.18 ))) for male and L, = 113.86(1 - exp(- 0.43(1- 0.74))) for female A. gilli from the Rondegat River. In the Noordhoeks River, growth was L, = 99.67(1 - exp(- 0.53(t - 0.35))) for male and L, = 96.60(1 - exp(- 0.64(t - 0.11 ))) for female A. gilli, and L, =71.02(1-exp(-0.26(1-3.07))) and L, = 69.50(1-exp(-0.36(1 - 1.88))) for male and female A. barnardi, respectively. The average natural mortality for the combined sexes was estimated using catch curve analysis at 0.37 ± 0.12 per year for A. gilli from the Rondegat River, and at 0.71 ± 0.05 and 0.39 ± 0.04 per year for A. gilli and A. barnardi from the Noordhoeks River, respectively. For A. gilli in the Rondegat River, the first maturity was estimated at 3.3 years (97.3 mm SL) for males and 3.1 years (94.3 mm SL) for females. In the Noordhoeks River, the first maturity for A. gilli was estimated at 2.0 years (71.9 mm SL) for males and 1.7 (66.4 mm SL) for females, and for A. barnardi at 2.0 (55.0 nun SL) for males and 2.9 years (58.9 mm SL) for females. Maturity corresponded closely to the asymptotic sizes from the von Bertalanffy curves, suggesting a shift in energy use from somatic growth to gonad development. Macroscopic assessment of the state of gonads, the Ganado-somatic index and histological examinations revealed that both A. gilli and A. barnardi have a single spawning season. The presence of oocytes in different stages of development in each of the ovaries of mature females collected between November and January suggested asynchronous, iteroperous serial spawning. The resorption of yolk was observed from ovaries collected between February and March and no vitellogenic oocyte was visible from ovaries collected between April and August. A similar trend was observed for males, with spermatozoa filling the lumen between November and January and some residual spermatozoa being present in the lumens soon after the breeding season. Spermatocytes and spermatids were dominant in the testes until October. An Index of Relative Importance revealed that A. gilli feeds predominantly on the benthic macroinvertebrate larvae of Ephemeroptera (particularly Baetidae), Diptera (particularly Chironomidae and Simuliidae) and Trichoptera. Austroglanis barnardi feeds predominantly on dipteran larvae (particularly Chironornidae and Simuliidae). Chi square contingency tables showed a significant difference in the dominant prey items of A. gilli and A. barnardi in the Noordhoeks River (X₂= 53.79, d.f. = 4, p > 0.001) and A. gilli between Rondegat and Noordhoeks rivers (x₂ = 34.74, d.f. = 4, p > 0.001). The Spearman's rank correlation test showed no shifts in the diet of A. barnardi from Noordhoeks River and A. gilli from Rondegat River with a change in size and season (p>O.OS). However, there was a shift in the diet of A. gilli from the Noordhoeks River which could suggest a distinct patchiness of benthic macroinvertebrates between the riffle feeding areas used by juveniles and other biotopes used by adults. The occurrence, in stomach contents, of other prey items from a wide variety of taxa and the presence of allochthonous material from the terrestrial environment could suggest an opportunistic feeding guild for both Austroglanis species. The life-history traits of A. gilli and A. barnardi, which are charaterized by slow growth, long life span and low relative fecundity, indicate that both species are relatively precocial and K-selected. The population of a precocial species is relatively stable and if population numbers were to be greatly reduced, they would require a long time to rebuild. An urgent conservation intervention is therefore recommended for Austroglanis spp. so as to maintain the diversity of populations within these species. The creation of protected river reserves and raising public conservation awareness may minimise activities that result in altered river hydrology and the destruction of complex benthic habitats.
- Full Text:
- Date Issued: 2010
- Authors: Mthombeni, Vusi Gedla
- Date: 2010
- Subjects: Catfishes -- South Africa -- Olifants River , Fishes -- South Africa -- Olifants River -- Growth , Freshwater fishes -- Effect of pesticides on -- South Africa -- Olifants River
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5370 , http://hdl.handle.net/10962/d1015222
- Description: Austroglanis gilli and A. barnardi are endemic to the Clanwilliam-Olifants System in the Western Cape, South Africa. The populations of each of these species are considered to be threatened by various anthropogenic activities, which include inappropriate agricultural practice and impacts of alien invasive fish species. The purpose of this thesis was to assess the life-history of these two endangered species in order to contribute to understanding their biology. Such information is vital for the development of strategies for their conservation. Marginal zone and marginal increment analyses from sectioned lapilliar otoliths of both A. gilli and A. barnardi showed a unimodal peak, suggesting a single annulus formation. The oldest specimens of A. gilli and A. barnardi were 12+ and 14+ years, respectively. The growth of A. gilli and A. barnardi was relatively slow and was best described by the von Bertalanffy growth curve as: L, = 131.56(1 - exp(- 0.27(t - 1.18 ))) for male and L, = 113.86(1 - exp(- 0.43(1- 0.74))) for female A. gilli from the Rondegat River. In the Noordhoeks River, growth was L, = 99.67(1 - exp(- 0.53(t - 0.35))) for male and L, = 96.60(1 - exp(- 0.64(t - 0.11 ))) for female A. gilli, and L, =71.02(1-exp(-0.26(1-3.07))) and L, = 69.50(1-exp(-0.36(1 - 1.88))) for male and female A. barnardi, respectively. The average natural mortality for the combined sexes was estimated using catch curve analysis at 0.37 ± 0.12 per year for A. gilli from the Rondegat River, and at 0.71 ± 0.05 and 0.39 ± 0.04 per year for A. gilli and A. barnardi from the Noordhoeks River, respectively. For A. gilli in the Rondegat River, the first maturity was estimated at 3.3 years (97.3 mm SL) for males and 3.1 years (94.3 mm SL) for females. In the Noordhoeks River, the first maturity for A. gilli was estimated at 2.0 years (71.9 mm SL) for males and 1.7 (66.4 mm SL) for females, and for A. barnardi at 2.0 (55.0 nun SL) for males and 2.9 years (58.9 mm SL) for females. Maturity corresponded closely to the asymptotic sizes from the von Bertalanffy curves, suggesting a shift in energy use from somatic growth to gonad development. Macroscopic assessment of the state of gonads, the Ganado-somatic index and histological examinations revealed that both A. gilli and A. barnardi have a single spawning season. The presence of oocytes in different stages of development in each of the ovaries of mature females collected between November and January suggested asynchronous, iteroperous serial spawning. The resorption of yolk was observed from ovaries collected between February and March and no vitellogenic oocyte was visible from ovaries collected between April and August. A similar trend was observed for males, with spermatozoa filling the lumen between November and January and some residual spermatozoa being present in the lumens soon after the breeding season. Spermatocytes and spermatids were dominant in the testes until October. An Index of Relative Importance revealed that A. gilli feeds predominantly on the benthic macroinvertebrate larvae of Ephemeroptera (particularly Baetidae), Diptera (particularly Chironomidae and Simuliidae) and Trichoptera. Austroglanis barnardi feeds predominantly on dipteran larvae (particularly Chironornidae and Simuliidae). Chi square contingency tables showed a significant difference in the dominant prey items of A. gilli and A. barnardi in the Noordhoeks River (X₂= 53.79, d.f. = 4, p > 0.001) and A. gilli between Rondegat and Noordhoeks rivers (x₂ = 34.74, d.f. = 4, p > 0.001). The Spearman's rank correlation test showed no shifts in the diet of A. barnardi from Noordhoeks River and A. gilli from Rondegat River with a change in size and season (p>O.OS). However, there was a shift in the diet of A. gilli from the Noordhoeks River which could suggest a distinct patchiness of benthic macroinvertebrates between the riffle feeding areas used by juveniles and other biotopes used by adults. The occurrence, in stomach contents, of other prey items from a wide variety of taxa and the presence of allochthonous material from the terrestrial environment could suggest an opportunistic feeding guild for both Austroglanis species. The life-history traits of A. gilli and A. barnardi, which are charaterized by slow growth, long life span and low relative fecundity, indicate that both species are relatively precocial and K-selected. The population of a precocial species is relatively stable and if population numbers were to be greatly reduced, they would require a long time to rebuild. An urgent conservation intervention is therefore recommended for Austroglanis spp. so as to maintain the diversity of populations within these species. The creation of protected river reserves and raising public conservation awareness may minimise activities that result in altered river hydrology and the destruction of complex benthic habitats.
- Full Text:
- Date Issued: 2010
Effect of repeated eccentric demands placed on the lower limb musculature during simulated Rugby Union play
- Authors: Brown, Lisa Gill
- Date: 2010
- Subjects: Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5114 , http://hdl.handle.net/10962/d1005192 , Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Description: Epidemiological studies consistently report that muscular strains are a primary injury type in rugby union with the majority of the strains occurring to the quadricep and hamstring musculature. Recently it has been suggested that poor eccentric muscular strength is a precursor to hamstring and quadriceps strains during intermittent sports that require rapid acceleration and deceleration. Despite the high incidence of these muscle injuries in Rugby Union there has been little research into the possible mechanisms involved. Thus, the purpose of this study was to measure the physiological and perceptual responses during a simulated Rugby Union laboratory protocol and further, to identify changes in muscle recruitment patterns and muscle strength over time by comparing this protocol to a continuous, constant load protocol covering the same distance. The experimental condition (EXP) required university level players to perform 80 minutes of simulated rugby union play in a laboratory setting (on a walkway of 22m) which was compared to that of a control condition (CON) which involved subjects covering the same distance, at a constant speed of 4.2km.h-1 on a treadmill. Physiological, biophysical and perceptual responses were measured pre-, at half-time and post-protocol. Heart rate was significantly (p<0.01) greater as a result of EXP in comparison to the CON. Electromyography (EMG) of the vastus medialis was significantly (p<0.01) greater during the CON protocol. The EXP condition elicited higher iEMG activity in the hamstring musculature at all time intervals. In addition the iEMG of the semitendinosus decreased significantly (p<0.01) as a result of the EXP protocol. Peak eccentric knee extensors (EXT) (-13.19%) and flexors (FLEX) (-12.81%) torque decreased significantly during the experimental protocol. After passive half-time (236.67 + 56.27Nm (EXT) and 173.89 + 33.3NM (FLEX)) and at the end of the protocol (220.39 + 55.16Nm and 162.89 + 30.66Nm) reduced relative to pre protocol (253.89 + 54.54Nm and 186.83 + 33.3Nm). Peak eccentric knee extensors did not change during the control protocol. „Central‟ and ‟Local” Rating of Perceived Exertion values were significantly (P<0.01) greater during the EXP protocol with an increased incidence of hamstring discomfort and perceived pain (5 out of 10). The EXP protocol resulted in significantly (p<0.01) increased incidence of delayed onset muscle soreness (DOMS). In conclusion, a stop-start laboratory protocol elicited increased heart rate, negatively impacted on muscle activity of the hamstrings, decreased eccentric strength in the lower limb musculature, resulted in increased ratings of „Central‟ and „Local‟ exertion and increased pain perception and increased incidence of DOMS. Thus, a stop-start rugby specific laboratory protocol has a negative impact on performance. Due to the specificity of the protocol being designed to match the demands of competitive match play it is expected that these changes in heart rate, muscle activity and strength, particularly eccentric strength, will impact negativity on performance during rugby match play and increase the likelihood of injury
- Full Text:
- Date Issued: 2010
- Authors: Brown, Lisa Gill
- Date: 2010
- Subjects: Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5114 , http://hdl.handle.net/10962/d1005192 , Sports injuries , Muscles -- Wounds and injuries , Tendons -- Wounds and injuries , Muscles -- Examination , Rugby football injuries , Rugby Union football players
- Description: Epidemiological studies consistently report that muscular strains are a primary injury type in rugby union with the majority of the strains occurring to the quadricep and hamstring musculature. Recently it has been suggested that poor eccentric muscular strength is a precursor to hamstring and quadriceps strains during intermittent sports that require rapid acceleration and deceleration. Despite the high incidence of these muscle injuries in Rugby Union there has been little research into the possible mechanisms involved. Thus, the purpose of this study was to measure the physiological and perceptual responses during a simulated Rugby Union laboratory protocol and further, to identify changes in muscle recruitment patterns and muscle strength over time by comparing this protocol to a continuous, constant load protocol covering the same distance. The experimental condition (EXP) required university level players to perform 80 minutes of simulated rugby union play in a laboratory setting (on a walkway of 22m) which was compared to that of a control condition (CON) which involved subjects covering the same distance, at a constant speed of 4.2km.h-1 on a treadmill. Physiological, biophysical and perceptual responses were measured pre-, at half-time and post-protocol. Heart rate was significantly (p<0.01) greater as a result of EXP in comparison to the CON. Electromyography (EMG) of the vastus medialis was significantly (p<0.01) greater during the CON protocol. The EXP condition elicited higher iEMG activity in the hamstring musculature at all time intervals. In addition the iEMG of the semitendinosus decreased significantly (p<0.01) as a result of the EXP protocol. Peak eccentric knee extensors (EXT) (-13.19%) and flexors (FLEX) (-12.81%) torque decreased significantly during the experimental protocol. After passive half-time (236.67 + 56.27Nm (EXT) and 173.89 + 33.3NM (FLEX)) and at the end of the protocol (220.39 + 55.16Nm and 162.89 + 30.66Nm) reduced relative to pre protocol (253.89 + 54.54Nm and 186.83 + 33.3Nm). Peak eccentric knee extensors did not change during the control protocol. „Central‟ and ‟Local” Rating of Perceived Exertion values were significantly (P<0.01) greater during the EXP protocol with an increased incidence of hamstring discomfort and perceived pain (5 out of 10). The EXP protocol resulted in significantly (p<0.01) increased incidence of delayed onset muscle soreness (DOMS). In conclusion, a stop-start laboratory protocol elicited increased heart rate, negatively impacted on muscle activity of the hamstrings, decreased eccentric strength in the lower limb musculature, resulted in increased ratings of „Central‟ and „Local‟ exertion and increased pain perception and increased incidence of DOMS. Thus, a stop-start rugby specific laboratory protocol has a negative impact on performance. Due to the specificity of the protocol being designed to match the demands of competitive match play it is expected that these changes in heart rate, muscle activity and strength, particularly eccentric strength, will impact negativity on performance during rugby match play and increase the likelihood of injury
- Full Text:
- Date Issued: 2010
Unionism and public service reform in Lesotho: between legislative constraints and apathy
- Authors: Maema, Mapule
- Date: 2010
- Subjects: Civil service -- Lesotho , Labor unions -- Lesotho , Civil service reform -- Lesotho
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3306 , http://hdl.handle.net/10962/d1003094 , Civil service -- Lesotho , Labor unions -- Lesotho , Civil service reform -- Lesotho
- Description: The study focuses on Lesotho‟s Public Service. The aims of this study were to examine the factors that led to the repeal of the Public Service Act No.13 of 1995. This study looks at the legislative constraints and attitudes of civil servants towards unionisation in the Public Service. It also outlines the relevant provisions of the Public Service Act No.1 of 2005; the changes that have occurred since its inception. Findings show that the Public Service Act No.13 of 1995 was repealed in order to reform the Public Service. The Ministry of the Public Service implemented five-year strategic plans to reform the public service. Changes have occurred in the public service since the inception of the 2005 Act; however, they differ from ministry to ministry. The respondents included public officers from the Ministry of the Public Service, Ministry of Justice, Law Office, Ministry of Employment and Labour, Ministry of Planning, the Ombudsman Office, Parliament, different ministries, the International Labour Organisation (ILO), the Congress of the Lesotho Trade Unions (COLETU) and the Lesotho Public Service Staff Association (LEPSSA).
- Full Text:
- Date Issued: 2010
- Authors: Maema, Mapule
- Date: 2010
- Subjects: Civil service -- Lesotho , Labor unions -- Lesotho , Civil service reform -- Lesotho
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3306 , http://hdl.handle.net/10962/d1003094 , Civil service -- Lesotho , Labor unions -- Lesotho , Civil service reform -- Lesotho
- Description: The study focuses on Lesotho‟s Public Service. The aims of this study were to examine the factors that led to the repeal of the Public Service Act No.13 of 1995. This study looks at the legislative constraints and attitudes of civil servants towards unionisation in the Public Service. It also outlines the relevant provisions of the Public Service Act No.1 of 2005; the changes that have occurred since its inception. Findings show that the Public Service Act No.13 of 1995 was repealed in order to reform the Public Service. The Ministry of the Public Service implemented five-year strategic plans to reform the public service. Changes have occurred in the public service since the inception of the 2005 Act; however, they differ from ministry to ministry. The respondents included public officers from the Ministry of the Public Service, Ministry of Justice, Law Office, Ministry of Employment and Labour, Ministry of Planning, the Ombudsman Office, Parliament, different ministries, the International Labour Organisation (ILO), the Congress of the Lesotho Trade Unions (COLETU) and the Lesotho Public Service Staff Association (LEPSSA).
- Full Text:
- Date Issued: 2010
An investigation into parental involvements in the learning of mathematics : a case study involving grade 5 San learners and their parents
- Hamukwaya, Shemunyenge Taleiko
- Authors: Hamukwaya, Shemunyenge Taleiko
- Date: 2010
- Subjects: Mathematics (Elementary) -- Study and teaching -- Namibia , Mathematics (Elementary) -- Study and teaching -- Activity programs -- Namibia , Mathematics (Elementary) -- Study and teaching -- Parent participation -- Namibia , Parent-teacher relationships -- Namibia , Marginality, Social -- Namibia , Literacy -- Social aspects -- Namibia , Khoisan (African people) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1598 , http://hdl.handle.net/10962/d1003480 , Mathematics (Elementary) -- Study and teaching -- Namibia , Mathematics (Elementary) -- Study and teaching -- Activity programs -- Namibia , Mathematics (Elementary) -- Study and teaching -- Parent participation -- Namibia , Parent-teacher relationships -- Namibia , Marginality, Social -- Namibia , Literacy -- Social aspects -- Namibia , Khoisan (African people) -- Namibia
- Description: The purpose of this study was to investigate and document parental involvement in a San community in Namibia over a period of two months. The emphasis was to investigate whether San parents in the Omusati region were involved in the learning of mathematics of their children. The learner participants were selected according to those who were open to sharing their ideas. An interpretive approach was used to collect and analyse data. The collected data was gathered from 9 participants (4 learners in grade 5 together with their parents, plus their mathematics teacher). Semi-structured interviews, parental contributions and home visit observations were the three tools that I used to collect data. The selected school is located in a rural area in the Omusati region of northern Namibia. The interviews were conducted in Oshiwambo (the participants‟ mother tongue) and translated into English and then analyzed. I discovered that the selected San parents were involved in some but limited school activities. The findings of this study emphasizes that illiteracy may be one of the contributing factors of low or non-involvement of parents among the San community. Other factors which I found caused parents not to assist their children with homework was parents spending much of their time at the local cuca shops during the day until late in the evenings. The study also highlights possible strategies that can be carried out by teachers to encourage parental involvement in school activities.
- Full Text:
- Date Issued: 2010
- Authors: Hamukwaya, Shemunyenge Taleiko
- Date: 2010
- Subjects: Mathematics (Elementary) -- Study and teaching -- Namibia , Mathematics (Elementary) -- Study and teaching -- Activity programs -- Namibia , Mathematics (Elementary) -- Study and teaching -- Parent participation -- Namibia , Parent-teacher relationships -- Namibia , Marginality, Social -- Namibia , Literacy -- Social aspects -- Namibia , Khoisan (African people) -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1598 , http://hdl.handle.net/10962/d1003480 , Mathematics (Elementary) -- Study and teaching -- Namibia , Mathematics (Elementary) -- Study and teaching -- Activity programs -- Namibia , Mathematics (Elementary) -- Study and teaching -- Parent participation -- Namibia , Parent-teacher relationships -- Namibia , Marginality, Social -- Namibia , Literacy -- Social aspects -- Namibia , Khoisan (African people) -- Namibia
- Description: The purpose of this study was to investigate and document parental involvement in a San community in Namibia over a period of two months. The emphasis was to investigate whether San parents in the Omusati region were involved in the learning of mathematics of their children. The learner participants were selected according to those who were open to sharing their ideas. An interpretive approach was used to collect and analyse data. The collected data was gathered from 9 participants (4 learners in grade 5 together with their parents, plus their mathematics teacher). Semi-structured interviews, parental contributions and home visit observations were the three tools that I used to collect data. The selected school is located in a rural area in the Omusati region of northern Namibia. The interviews were conducted in Oshiwambo (the participants‟ mother tongue) and translated into English and then analyzed. I discovered that the selected San parents were involved in some but limited school activities. The findings of this study emphasizes that illiteracy may be one of the contributing factors of low or non-involvement of parents among the San community. Other factors which I found caused parents not to assist their children with homework was parents spending much of their time at the local cuca shops during the day until late in the evenings. The study also highlights possible strategies that can be carried out by teachers to encourage parental involvement in school activities.
- Full Text:
- Date Issued: 2010
Social relationships and identity online and offline: a study of the interplay between offline social relationships and facebook usage by Rhodes University students from socially disadvantaged backgrounds
- Authors: Chatora, Arther Tichaona
- Date: 2010
- Subjects: Facebook (Electronic resource) Online social networks Information technology -- Social aspects Identity (Psychology) and mass media Rhodes University -- Students -- Social life and customs Rhodes University -- Students -- Social networks Rhodes University -- Students -- Social conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3421 , http://hdl.handle.net/10962/d1002874
- Description: Based on in-depth focus group and individual interviews, this thesis examines how Rhodes University students from socially disadvantaged backgrounds experience campus social life and how they subsequently use Facebook to perform, represent and negotiate their social identities. The study discusses utopian and dystopian positions and interrogates these theoretical perspectives in relation to the students‟ Facebook usage. The popularity and uptake of Facebook by students from disadvantaged backgrounds, such as those here at Rhodes University, is a growing phenomenon, provoking questions about the relationship between social experiences, social identity and social networks. Rhodes University‟s social space has been identified by previous studies as modern, liberal, “elite” and divided along race and class lines. The ways in which students experience this campus social space relates to their subject positions and identities. The study employs different perspectives of identity construction to interrogate the students‟ subject experiences in home and school contexts before coming to Rhodes University. The students‟ subjective positions are primarily embedded in tradition and their subject positions are sometimes in tension or come in conflict with the modern and liberal elements permitted by the Rhodes University context. The students also experience and adopt modern and liberal elements in their lifestyles which are permitted within the Rhodes University social space. The thesis found that Facebook offers a platform which facilitates a social connectivity that influences how students perform their identities in relation to their offline social identities and lived social experiences. This study concludes that the mediated symbolic materials for the construction and negotiation of identity provided by Facebook are sometimes in tension with the demands of traditional subjectivities experienced by these students at Rhodes University. Facebook allows the students to reinforce and affirm the validity of their traditional identities in this modern and liberal space. However, it also emerged that Facebook facilitates and allows students who experience and incorporate the modern and liberal elements permitted at Rhodes University to represent and negotiate their subjective positions online. The findings of the study indicate that participants primarily communicate with their friends, families, relatives and acquaintances - people they know personally offline, in line with the theoretical position which argues that online relationships are primarily shaped by offline relationships.
- Full Text:
- Date Issued: 2010
- Authors: Chatora, Arther Tichaona
- Date: 2010
- Subjects: Facebook (Electronic resource) Online social networks Information technology -- Social aspects Identity (Psychology) and mass media Rhodes University -- Students -- Social life and customs Rhodes University -- Students -- Social networks Rhodes University -- Students -- Social conditions
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3421 , http://hdl.handle.net/10962/d1002874
- Description: Based on in-depth focus group and individual interviews, this thesis examines how Rhodes University students from socially disadvantaged backgrounds experience campus social life and how they subsequently use Facebook to perform, represent and negotiate their social identities. The study discusses utopian and dystopian positions and interrogates these theoretical perspectives in relation to the students‟ Facebook usage. The popularity and uptake of Facebook by students from disadvantaged backgrounds, such as those here at Rhodes University, is a growing phenomenon, provoking questions about the relationship between social experiences, social identity and social networks. Rhodes University‟s social space has been identified by previous studies as modern, liberal, “elite” and divided along race and class lines. The ways in which students experience this campus social space relates to their subject positions and identities. The study employs different perspectives of identity construction to interrogate the students‟ subject experiences in home and school contexts before coming to Rhodes University. The students‟ subjective positions are primarily embedded in tradition and their subject positions are sometimes in tension or come in conflict with the modern and liberal elements permitted by the Rhodes University context. The students also experience and adopt modern and liberal elements in their lifestyles which are permitted within the Rhodes University social space. The thesis found that Facebook offers a platform which facilitates a social connectivity that influences how students perform their identities in relation to their offline social identities and lived social experiences. This study concludes that the mediated symbolic materials for the construction and negotiation of identity provided by Facebook are sometimes in tension with the demands of traditional subjectivities experienced by these students at Rhodes University. Facebook allows the students to reinforce and affirm the validity of their traditional identities in this modern and liberal space. However, it also emerged that Facebook facilitates and allows students who experience and incorporate the modern and liberal elements permitted at Rhodes University to represent and negotiate their subjective positions online. The findings of the study indicate that participants primarily communicate with their friends, families, relatives and acquaintances - people they know personally offline, in line with the theoretical position which argues that online relationships are primarily shaped by offline relationships.
- Full Text:
- Date Issued: 2010
A contribution to TEC modelling over Southern Africa using GPS data
- Authors: Habarulema, John Bosco
- Date: 2010
- Subjects: Electrons -- Mathematical models Radio wave propagation Global positioning system -- Measurement Ionospheric radio wave propagation Atmospheric physics -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5456 , http://hdl.handle.net/10962/d1005241
- Description: Modelling ionospheric total electron content (TEC) is an important area of interest for radio wave propagation, geodesy, surveying, the understanding of space weather dynamics and error correction in relation to Global Navigation Satellite Systems (GNNS) applications. With the utilisation of improved ionosonde technology coupled with the use of GNSS, the response of technological systems due to changes in the ionosphere during both quiet and disturbed conditions can be historically inferred. TEC values are usually derived from GNSS measurements using mathematically intensive algorithms. However, the techniques used to estimate these TEC values depend heavily on the availability of near-real time GNSS data, and therefore, are sometimes unable to generate complete datasets. This thesis investigated possibilities for the modelling of TEC values derived from the South African Global Positioning System (GPS)receiver network using linear regression methods and artificial neural networks (NNs). GPS TEC values were derived using the Adjusted Spherical Harmonic Analysis (ASHA) algorithm. Considering TEC and the factors that influence its variability as “dependent and independent variables” respectively, the capabilities of linear regression methods and NNs for TEC modelling were first investigated using a small dataset from two GPS receiver stations. NN and regression models were separately developed and used to reproduce TEC fluctuations at different stations not included in the models’ development. For this purpose, TEC was modelled as a function of diurnal variation, seasonal variation, solar and magnetic activities. Comparative analysis showed that NN models provide predictions of GPS TEC that were an improvement on those predicted by the regression models developed. A separate study to empirically investigate the effects of solar wind on GPS TEC was carried out. Quantitative results indicated that solar wind does not have a significant influence on TEC variability. The final TEC simulation model developed makes use of the NN technique to find the relationship between historical TEC data variations and factors that are known to influence TEC variability (such as solar and magnetic activities, diurnal and seasonal variations and the geographical locations of the respective GPS stations) for the purposes of regional TEC modelling and mapping. The NN technique in conjunction with interpolation and extrapolation methods makes it possible to construct ionospheric TEC maps and to analyse the spatial and temporal TEC behaviour over Southern Africa. For independent validation, modelled TEC values were compared to ionosonde TEC and the International Reference Ionosphere (IRI) generated TEC values during both quiet and disturbed conditions. This thesis provides a comprehensive guide on the development of TEC models for predicting ionospheric variability over the South African region, and forms a significant contribution to ionospheric modelling efforts in Africa.
- Full Text:
- Date Issued: 2010
- Authors: Habarulema, John Bosco
- Date: 2010
- Subjects: Electrons -- Mathematical models Radio wave propagation Global positioning system -- Measurement Ionospheric radio wave propagation Atmospheric physics -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5456 , http://hdl.handle.net/10962/d1005241
- Description: Modelling ionospheric total electron content (TEC) is an important area of interest for radio wave propagation, geodesy, surveying, the understanding of space weather dynamics and error correction in relation to Global Navigation Satellite Systems (GNNS) applications. With the utilisation of improved ionosonde technology coupled with the use of GNSS, the response of technological systems due to changes in the ionosphere during both quiet and disturbed conditions can be historically inferred. TEC values are usually derived from GNSS measurements using mathematically intensive algorithms. However, the techniques used to estimate these TEC values depend heavily on the availability of near-real time GNSS data, and therefore, are sometimes unable to generate complete datasets. This thesis investigated possibilities for the modelling of TEC values derived from the South African Global Positioning System (GPS)receiver network using linear regression methods and artificial neural networks (NNs). GPS TEC values were derived using the Adjusted Spherical Harmonic Analysis (ASHA) algorithm. Considering TEC and the factors that influence its variability as “dependent and independent variables” respectively, the capabilities of linear regression methods and NNs for TEC modelling were first investigated using a small dataset from two GPS receiver stations. NN and regression models were separately developed and used to reproduce TEC fluctuations at different stations not included in the models’ development. For this purpose, TEC was modelled as a function of diurnal variation, seasonal variation, solar and magnetic activities. Comparative analysis showed that NN models provide predictions of GPS TEC that were an improvement on those predicted by the regression models developed. A separate study to empirically investigate the effects of solar wind on GPS TEC was carried out. Quantitative results indicated that solar wind does not have a significant influence on TEC variability. The final TEC simulation model developed makes use of the NN technique to find the relationship between historical TEC data variations and factors that are known to influence TEC variability (such as solar and magnetic activities, diurnal and seasonal variations and the geographical locations of the respective GPS stations) for the purposes of regional TEC modelling and mapping. The NN technique in conjunction with interpolation and extrapolation methods makes it possible to construct ionospheric TEC maps and to analyse the spatial and temporal TEC behaviour over Southern Africa. For independent validation, modelled TEC values were compared to ionosonde TEC and the International Reference Ionosphere (IRI) generated TEC values during both quiet and disturbed conditions. This thesis provides a comprehensive guide on the development of TEC models for predicting ionospheric variability over the South African region, and forms a significant contribution to ionospheric modelling efforts in Africa.
- Full Text:
- Date Issued: 2010
A critical investigation of the interpretation and implementation of the Parzival main lesson within the context of the Waldorf curriculum : a multiple case study
- Authors: Swanepoel, Elizabeth
- Date: 2010
- Subjects: Waldorf method of education Education -- Philosophy Teaching -- South Africa Perceval (Legendary character) Perceval (Legendary character) -- Study and teaching Grail Legends -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1483 , http://hdl.handle.net/10962/d1003364
- Description: The Steiner/Waldorf school movement is currently one of the fastest growing independent school movements internationally. In several countries it seems to have developed into the most popular form of alternative education. South Africa has 17 Waldorf schools and one full-time teacher training facility. This study investigated the interpretation and implementation of the Parzival main lesson within the wider context of the Waldorf curriculum. The main lesson system is an essential constituent of the Waldorf curriculum. Most academic subjects in a Waldorf school are taught in a three- or four-week main lesson block. The main lesson occupies the first two hours of the school day. A main lesson consists of a particular three-part structure, and the main lesson book is the keystone to the Waldorf evaluative process. The Parzival main lesson is specifically taught in Class 11, and most Waldorf schools consider it as one of the most important main lessons in the high school. The interpretivist model was ideally suited to this research. The investigation was conducted as a multiple case study, and the main source of data was provided by classroom observation. This was supported by interviews and classroom artifacts. The study involved two South African Waldorf schools at which the Parzival main lesson is taught. This main lesson is presented at only three South African Waldorf schools. I teach at the remaining school, and therefore conducted my research at the other two schools. The teachers who facilitated the Parzival main lesson, as well as the Class students at the selected schools voluntarily participated in the research. My research findings indicate that the possibility exists for the teacher to exercise a certain degree of freedom and creativity within the parameters of Waldorf methodology and the Waldorf curriculum. The study also determines that teachers often find it difficult to integrate the three-part structure, as indicated by Waldorf methodology, in a single main lesson. Furthermore, my research establishes that main lesson books can indeed serve as both text and as an assessment tool. I therefore conclude and maintain in this study, with particular reference to the Parzival main lesson, that despite the prescriptive structure of the Waldorf system and Steiner pedagogy, teachers need not necessarily sacrifice their freedom and creativity within the classroom.
- Full Text:
- Date Issued: 2010
- Authors: Swanepoel, Elizabeth
- Date: 2010
- Subjects: Waldorf method of education Education -- Philosophy Teaching -- South Africa Perceval (Legendary character) Perceval (Legendary character) -- Study and teaching Grail Legends -- Study and teaching
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1483 , http://hdl.handle.net/10962/d1003364
- Description: The Steiner/Waldorf school movement is currently one of the fastest growing independent school movements internationally. In several countries it seems to have developed into the most popular form of alternative education. South Africa has 17 Waldorf schools and one full-time teacher training facility. This study investigated the interpretation and implementation of the Parzival main lesson within the wider context of the Waldorf curriculum. The main lesson system is an essential constituent of the Waldorf curriculum. Most academic subjects in a Waldorf school are taught in a three- or four-week main lesson block. The main lesson occupies the first two hours of the school day. A main lesson consists of a particular three-part structure, and the main lesson book is the keystone to the Waldorf evaluative process. The Parzival main lesson is specifically taught in Class 11, and most Waldorf schools consider it as one of the most important main lessons in the high school. The interpretivist model was ideally suited to this research. The investigation was conducted as a multiple case study, and the main source of data was provided by classroom observation. This was supported by interviews and classroom artifacts. The study involved two South African Waldorf schools at which the Parzival main lesson is taught. This main lesson is presented at only three South African Waldorf schools. I teach at the remaining school, and therefore conducted my research at the other two schools. The teachers who facilitated the Parzival main lesson, as well as the Class students at the selected schools voluntarily participated in the research. My research findings indicate that the possibility exists for the teacher to exercise a certain degree of freedom and creativity within the parameters of Waldorf methodology and the Waldorf curriculum. The study also determines that teachers often find it difficult to integrate the three-part structure, as indicated by Waldorf methodology, in a single main lesson. Furthermore, my research establishes that main lesson books can indeed serve as both text and as an assessment tool. I therefore conclude and maintain in this study, with particular reference to the Parzival main lesson, that despite the prescriptive structure of the Waldorf system and Steiner pedagogy, teachers need not necessarily sacrifice their freedom and creativity within the classroom.
- Full Text:
- Date Issued: 2010
Formulation and evaluation of captopril loaded polymethacrylate and hydroxypropyl methycellulose microcapsules
- Khamanga, Sandile Maswazi Malungelo
- Authors: Khamanga, Sandile Maswazi Malungelo
- Date: 2010
- Subjects: Hypertension -- Treatment , Hypertension -- Chemotherapy , Angiotensin converting enzyme -- Inhibitors , Hypotensive agents -- Development , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3860 , http://hdl.handle.net/10962/d1013443
- Description: Angiotensin-converting enzyme (ACE) inhibitors are some of the most commonly prescribed medications for hypertension. They are cited in many papers as the treatment most often recommended by guidelines and favoured over other antihypertensive drugs as first-line agents especially when other high-risk conditions are present, such as diabetic nephropathy. The development of captopril (CPT) was amongst the earliest successes of the revolutionary concept of structure-based drug design. Due to its relatively poor pharmacokinetic profile or short half-life of about 1 hour, the formulation of sustained-release microcapsule dosage form is useful to improve patient compliance and to achieve predictable and optimized therapeutic plasma concentrations. Currently, CPT is mainly administered in tablet form. One of the difficulties of CPT formulation has been reported to be its instability in aqueous solutions. CPT is characterized by a lack of a strong chromophore and, therefore, not able to absorb at the more useful UV–Vis region of the spectrum. For this reason, an accurate, simple, reproducible, and sensitive HPLC-ECD method was developed and validated for the determination of CPT in dosage forms. The method was successfully applied for the determination of CPT in commercial and developed formulations. Possible drug-excipient and excipient-excipient interactions were investigated prior to formulating CPT microcapsules because successful formulation of a stable and effective solid dosage form depends on careful selection of excipients. Nuclear magnetic resonance spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for the identification and purity testing of CPT and excipients. The studies revealed no thermal changes during stress testing of binary and whole mixtures which indicate absence of solid state interactions. There were no shifts, appearance and disappearance in the endothermic or exothermic peaks and on the change of other associated enthalpy values on thermal curves obtained with DSC method. Characteristic peaks for common functional groups in the FT-IR were present in all the mixtures indicating the absence of incompatibility. The techniques used in this study can be said to have been efficient in the characterization and evaluation of the drug and excipients. The technique of microencapsulation by oil-in-oil was used to prepare CPT microcapsules. The effects of polymer molecular weight, homogenizing speed on the particle size, flow properties, morphology, surface properties and release characteristics of the prepared CPT microcapsules were examined. In order to decrease the complexity of the analysis and reduce cost response surface methodology using best polynomial equations was successfully used to quantify the effect of the formulation variables and develop an optimized formulation thereby minimizing the number of experimental trials. There was a burst effect during the first stage of dissolution. Scanning electron microscopy (SEM) results indicated that the initial burst effect observed in drug release could be attributed to dissolution of CPT crystals present at the surface or embedded in the superficial layer of the matrix. During the preparation of microcapsules, the drug might have been trapped near the surface of the microcapsules and or might have diffused quickly through the porous surface. The release kinetics of CPT from most formulations followed Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores at the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed predominance of diffusion relative to swelling or erosion throughout the entire test period. Drug release mechanism was also confirmed by Makoid-Banakar and Korsmeyer-Peppas models exponents which further support diffusion release mechanism in most formulations. The models postulate that the total of drug release is a summation of a couple of mechanisms; burst release, relaxation induced controlled-release and diffusional release. Inspection of the 2D contour and 3D response surfaces allowed the determination of the geometrical nature of the surfaces and further providing results about the interaction of the different variables used in central composite design (CCD). The wide variation indicated that the factor combinations resulted in different drug release rates. Lagrange, canonical and mathematical modelling were used to determine the nature of the stationery point of the models. This represented the optimal variables or stationery points where there is interaction in the experimental space. It is difficult to understand the shape of a fitted response by mere inspection of the algebraic polynomial when there are many independent variables in the model. Canonical and Lagrange analyses facilitated the interpretation of the surface plots after a mathematical transformation of the original variables into new variables. In conclusion, these results suggest the potential application of Eudragit® / Methocel® microcapsules as suitable sustained-release drug delivery system for CPT.
- Full Text:
- Date Issued: 2010
- Authors: Khamanga, Sandile Maswazi Malungelo
- Date: 2010
- Subjects: Hypertension -- Treatment , Hypertension -- Chemotherapy , Angiotensin converting enzyme -- Inhibitors , Hypotensive agents -- Development , Pharmacokinetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3860 , http://hdl.handle.net/10962/d1013443
- Description: Angiotensin-converting enzyme (ACE) inhibitors are some of the most commonly prescribed medications for hypertension. They are cited in many papers as the treatment most often recommended by guidelines and favoured over other antihypertensive drugs as first-line agents especially when other high-risk conditions are present, such as diabetic nephropathy. The development of captopril (CPT) was amongst the earliest successes of the revolutionary concept of structure-based drug design. Due to its relatively poor pharmacokinetic profile or short half-life of about 1 hour, the formulation of sustained-release microcapsule dosage form is useful to improve patient compliance and to achieve predictable and optimized therapeutic plasma concentrations. Currently, CPT is mainly administered in tablet form. One of the difficulties of CPT formulation has been reported to be its instability in aqueous solutions. CPT is characterized by a lack of a strong chromophore and, therefore, not able to absorb at the more useful UV–Vis region of the spectrum. For this reason, an accurate, simple, reproducible, and sensitive HPLC-ECD method was developed and validated for the determination of CPT in dosage forms. The method was successfully applied for the determination of CPT in commercial and developed formulations. Possible drug-excipient and excipient-excipient interactions were investigated prior to formulating CPT microcapsules because successful formulation of a stable and effective solid dosage form depends on careful selection of excipients. Nuclear magnetic resonance spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used for the identification and purity testing of CPT and excipients. The studies revealed no thermal changes during stress testing of binary and whole mixtures which indicate absence of solid state interactions. There were no shifts, appearance and disappearance in the endothermic or exothermic peaks and on the change of other associated enthalpy values on thermal curves obtained with DSC method. Characteristic peaks for common functional groups in the FT-IR were present in all the mixtures indicating the absence of incompatibility. The techniques used in this study can be said to have been efficient in the characterization and evaluation of the drug and excipients. The technique of microencapsulation by oil-in-oil was used to prepare CPT microcapsules. The effects of polymer molecular weight, homogenizing speed on the particle size, flow properties, morphology, surface properties and release characteristics of the prepared CPT microcapsules were examined. In order to decrease the complexity of the analysis and reduce cost response surface methodology using best polynomial equations was successfully used to quantify the effect of the formulation variables and develop an optimized formulation thereby minimizing the number of experimental trials. There was a burst effect during the first stage of dissolution. Scanning electron microscopy (SEM) results indicated that the initial burst effect observed in drug release could be attributed to dissolution of CPT crystals present at the surface or embedded in the superficial layer of the matrix. During the preparation of microcapsules, the drug might have been trapped near the surface of the microcapsules and or might have diffused quickly through the porous surface. The release kinetics of CPT from most formulations followed Fickian diffusion mechanism. SEM photographs showed that diffusion took place through pores at the surface of the microcapsules. The Kopcha model diffusion and erosion terms showed predominance of diffusion relative to swelling or erosion throughout the entire test period. Drug release mechanism was also confirmed by Makoid-Banakar and Korsmeyer-Peppas models exponents which further support diffusion release mechanism in most formulations. The models postulate that the total of drug release is a summation of a couple of mechanisms; burst release, relaxation induced controlled-release and diffusional release. Inspection of the 2D contour and 3D response surfaces allowed the determination of the geometrical nature of the surfaces and further providing results about the interaction of the different variables used in central composite design (CCD). The wide variation indicated that the factor combinations resulted in different drug release rates. Lagrange, canonical and mathematical modelling were used to determine the nature of the stationery point of the models. This represented the optimal variables or stationery points where there is interaction in the experimental space. It is difficult to understand the shape of a fitted response by mere inspection of the algebraic polynomial when there are many independent variables in the model. Canonical and Lagrange analyses facilitated the interpretation of the surface plots after a mathematical transformation of the original variables into new variables. In conclusion, these results suggest the potential application of Eudragit® / Methocel® microcapsules as suitable sustained-release drug delivery system for CPT.
- Full Text:
- Date Issued: 2010
Volatility and the risk return relationship on the South African equity market
- Authors: Mandimika, Neville
- Date: 2010
- Subjects: Stock exchanges , Financial risk -- South Africa , Saving and investment -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1009 , http://hdl.handle.net/10962/d1002744 , Stock exchanges , Financial risk -- South Africa , Saving and investment -- South Africa
- Description: The volatility of stock markets has important implications for investment decision making, financial stability and overall macroeconomic stability. This study examines the risk-return relationship as well as the behaviour of volatility of the South African equity markets using both aggregate, industrial level and sector level data. The study is divided into three parts. The first part investigates the behaviour of volatility in each of the industries, sectors and the benchmark series focussing on whether volatility is symmetric or asymmetric. Subsequently we investigate which, among the GARCH family of models appropriately captured the riskreturn relationship under which distributional assumption. The second part examines the riskreturn relationship on the SA stock market. The third part examines the long term trend of volatility and whether volatility significantly increases during financial crises and during major global shocks. The GARCH-M, EGARCH-M and TARCH-M models under the Gaussian, Student –t and the GED are used. The findings this study makes are as follows: firstly, there is no clear relationship between risk and return. Secondly, volatility is asymmetrical, implying that bad news has a greater effect on volatility than good news in the South African equity market. Thirdly, the TARCH-M model under the GED was found to be the most appropriate model. Fourthly, volatility increases during financial crises and major global shocks. Overall, volatility is generally not priced on the South African equity markets. Thus, both local and international investors need to consider other factors that influence returns such as skewness. The general increase in volatility during financial crises and major global shocks poses a major concern for policy makers as this may cause financial instability. Thus policy makers need to be mindful of the behaviour of volatility in the South African equity market in response to external shocks.
- Full Text:
- Date Issued: 2010
- Authors: Mandimika, Neville
- Date: 2010
- Subjects: Stock exchanges , Financial risk -- South Africa , Saving and investment -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1009 , http://hdl.handle.net/10962/d1002744 , Stock exchanges , Financial risk -- South Africa , Saving and investment -- South Africa
- Description: The volatility of stock markets has important implications for investment decision making, financial stability and overall macroeconomic stability. This study examines the risk-return relationship as well as the behaviour of volatility of the South African equity markets using both aggregate, industrial level and sector level data. The study is divided into three parts. The first part investigates the behaviour of volatility in each of the industries, sectors and the benchmark series focussing on whether volatility is symmetric or asymmetric. Subsequently we investigate which, among the GARCH family of models appropriately captured the riskreturn relationship under which distributional assumption. The second part examines the riskreturn relationship on the SA stock market. The third part examines the long term trend of volatility and whether volatility significantly increases during financial crises and during major global shocks. The GARCH-M, EGARCH-M and TARCH-M models under the Gaussian, Student –t and the GED are used. The findings this study makes are as follows: firstly, there is no clear relationship between risk and return. Secondly, volatility is asymmetrical, implying that bad news has a greater effect on volatility than good news in the South African equity market. Thirdly, the TARCH-M model under the GED was found to be the most appropriate model. Fourthly, volatility increases during financial crises and major global shocks. Overall, volatility is generally not priced on the South African equity markets. Thus, both local and international investors need to consider other factors that influence returns such as skewness. The general increase in volatility during financial crises and major global shocks poses a major concern for policy makers as this may cause financial instability. Thus policy makers need to be mindful of the behaviour of volatility in the South African equity market in response to external shocks.
- Full Text:
- Date Issued: 2010
Comparison of the neuroprotective potential of theanine and minocycline
- Authors: Mpofu, Tariro Ann-Maureen
- Date: 2010 , 2010-09-20
- Subjects: Nervous system -- Degeneration -- Treatment , Tetracyclines , Antibiotics -- Side effects , Theanine -- Evaluation , Drugs -- Administration , Cerebrovascular disease -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3775 , http://hdl.handle.net/10962/d1003253 , Nervous system -- Degeneration -- Treatment , Tetracyclines , Antibiotics -- Side effects , Theanine -- Evaluation , Drugs -- Administration , Cerebrovascular disease -- Prevention
- Description: Stroke is one of the most common causes of disability and death worldwide. The most commonly experienced stroke in the clinical setting is focal ischaemia in which the middle cerebral artery (MCA) is occluded and leads to a complex series of various pathophysiological pathways that ultimately lead to neuronal cell death. Several studies have been conducted on various therapeutic agents in the search for a neuroprotective drug and various animal models have been used to carry out this research. While theanine, a component of green tea and minocycline, a tetracycline antibiotic, have been shown to possess some neuroprotective properties, the mechanisms by which these two agents carry out these effects still remains unclear. The objectives of this study were to investigate the mechanisms by which these drugs carry out these neuroprotective effects and their neuroprotective ability in a MCA occlusion model of focal ischaemia. Ischaemia leads to oxidative stress due to the imbalance of free radicals and the endogenous antioxidant defence system. An antioxidant assay using the stable 2, 2-diphenyl-1-picrylhydrazyl (DPPH●) radical was used to assess the antiradical properties of each drug. It was found that minocycline showed superior antioxidant activity in vitro when compared to theanine. Further studies on the drugs‟ ability to attenuate the Fenton reaction (in which iron catalyses the formation of reactive species) were elucidated using electrochemical analysis, UV/VIS studies, ferrozine and ferritin assays. It was found that minocycline, in contrast to theanine, was able to bind to iron ions and thus potentially prevent the participation of iron in metal catalysed radical reaction. The antioxidant activity of both drugs was further investigated by assessing their effect on cyanide-induced superoxide generation and quinolinic acid (QA)-induced lipid peroxidation (LP). Experimental evidence shows that both drugs had no significant effect on the generation of superoxide in vitro and that there was a significant decrease in LP for minocycline in vitro and theanine in vivo. The metal binding and antioxidant properties were postulated to be a possible mechanism through which these agents reduced lipid peroxidation. A study was conducted to determine the effects of the drugs on the biosynthesis of the neurotoxin, QA and it was found that minocycline increases the levels of holoenzyme activity of tryptophan-2, 3-dioxygenase (TDO) in vitro and that theanine reduces the levels of the same enzyme in vivo after treatment for 10 days. TDO is the enzyme that converts tryptophan to other products that enable enzymatic activity to change it to QA. Minocycline was thought to bring about this effect as it has been shown from preceding experimental studies that it is an effective reducing agent. Theanine on the other hand is hypothesised to bring about a reduction in holoenzyme activity by changing the binding of tryptophan to the enzyme or affecting the radicals that participate in the enzymatic degradation of tryptophan. A focal ischaemic model of stroke was induced by occluding the MCA. Histological examination of the hippocampus post -ischaemia shows a reduction in the size of the infarct after pre-treatment with minocycline only. A further study into the effects of the drugs on the generation of superoxide and on the levels of the endogenous glutathione after a stroke was carried out. Pre-treatment of the animals with either theanine or minocycline showed no significant effects on the generation of the radical species or of the endogenous antioxidant which ruled out these as a mechanism of neuroprotection of both drugs, post-ischaemia.The findings of this study provide novel information on the possible mechanisms by which both theanine and minocycline act to bring about neuroprotection. In particular in this study, pre-treatment with minocycline has shown promise in the focal ischaemic model of stroke.
- Full Text:
- Date Issued: 2010
- Authors: Mpofu, Tariro Ann-Maureen
- Date: 2010 , 2010-09-20
- Subjects: Nervous system -- Degeneration -- Treatment , Tetracyclines , Antibiotics -- Side effects , Theanine -- Evaluation , Drugs -- Administration , Cerebrovascular disease -- Prevention
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3775 , http://hdl.handle.net/10962/d1003253 , Nervous system -- Degeneration -- Treatment , Tetracyclines , Antibiotics -- Side effects , Theanine -- Evaluation , Drugs -- Administration , Cerebrovascular disease -- Prevention
- Description: Stroke is one of the most common causes of disability and death worldwide. The most commonly experienced stroke in the clinical setting is focal ischaemia in which the middle cerebral artery (MCA) is occluded and leads to a complex series of various pathophysiological pathways that ultimately lead to neuronal cell death. Several studies have been conducted on various therapeutic agents in the search for a neuroprotective drug and various animal models have been used to carry out this research. While theanine, a component of green tea and minocycline, a tetracycline antibiotic, have been shown to possess some neuroprotective properties, the mechanisms by which these two agents carry out these effects still remains unclear. The objectives of this study were to investigate the mechanisms by which these drugs carry out these neuroprotective effects and their neuroprotective ability in a MCA occlusion model of focal ischaemia. Ischaemia leads to oxidative stress due to the imbalance of free radicals and the endogenous antioxidant defence system. An antioxidant assay using the stable 2, 2-diphenyl-1-picrylhydrazyl (DPPH●) radical was used to assess the antiradical properties of each drug. It was found that minocycline showed superior antioxidant activity in vitro when compared to theanine. Further studies on the drugs‟ ability to attenuate the Fenton reaction (in which iron catalyses the formation of reactive species) were elucidated using electrochemical analysis, UV/VIS studies, ferrozine and ferritin assays. It was found that minocycline, in contrast to theanine, was able to bind to iron ions and thus potentially prevent the participation of iron in metal catalysed radical reaction. The antioxidant activity of both drugs was further investigated by assessing their effect on cyanide-induced superoxide generation and quinolinic acid (QA)-induced lipid peroxidation (LP). Experimental evidence shows that both drugs had no significant effect on the generation of superoxide in vitro and that there was a significant decrease in LP for minocycline in vitro and theanine in vivo. The metal binding and antioxidant properties were postulated to be a possible mechanism through which these agents reduced lipid peroxidation. A study was conducted to determine the effects of the drugs on the biosynthesis of the neurotoxin, QA and it was found that minocycline increases the levels of holoenzyme activity of tryptophan-2, 3-dioxygenase (TDO) in vitro and that theanine reduces the levels of the same enzyme in vivo after treatment for 10 days. TDO is the enzyme that converts tryptophan to other products that enable enzymatic activity to change it to QA. Minocycline was thought to bring about this effect as it has been shown from preceding experimental studies that it is an effective reducing agent. Theanine on the other hand is hypothesised to bring about a reduction in holoenzyme activity by changing the binding of tryptophan to the enzyme or affecting the radicals that participate in the enzymatic degradation of tryptophan. A focal ischaemic model of stroke was induced by occluding the MCA. Histological examination of the hippocampus post -ischaemia shows a reduction in the size of the infarct after pre-treatment with minocycline only. A further study into the effects of the drugs on the generation of superoxide and on the levels of the endogenous glutathione after a stroke was carried out. Pre-treatment of the animals with either theanine or minocycline showed no significant effects on the generation of the radical species or of the endogenous antioxidant which ruled out these as a mechanism of neuroprotection of both drugs, post-ischaemia.The findings of this study provide novel information on the possible mechanisms by which both theanine and minocycline act to bring about neuroprotection. In particular in this study, pre-treatment with minocycline has shown promise in the focal ischaemic model of stroke.
- Full Text:
- Date Issued: 2010
Geology of the Kroonstad kimberlite cluster, South Africa
- Authors: Howarth, Geoffrey H
- Date: 2010
- Subjects: Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4961 , http://hdl.handle.net/10962/d1005573 , Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Description: The Cretaceous (133Ma) Kroonstad Group II Kimberlite Cluster is located approximately 200km south west of Johannesburg on the Kaapvaal Craton. The cluster is made up of six kimberlite pipes and numerous other intrusive dike/sill bodies. Three of the pipes are analysed in this study, which includes the: Voorspoed, Lace (Crown) and Besterskraal North pipes. These pipes were emplaced at surface into the Karoo Supergroup, which is comprised of older sedimentary rocks (300-185Ma) overlain by flood basalts (185Ma). At depth the pipes have intruded the Transvaal (2100-2600Ma) and Ventersdorp (2700Ma) Supergroups, which are comprised dominantly of carbonates and various volcanic units respectively. The pipes have typical morphology of South African pipes with circular to sub-circular plan views and steep 82o pipe margins. The Voorspoed pipe is 12ha in size and is characterised by the presence of a large block of Karoo basalt approximately 6ha in size at the current land surface. This large basalt block extends to a maximum of 300m below the current land surface. The main Lace pipe is 2ha is size with a smaller (<0.5ha) satellite pipe approximately 50m to the west. No information is available on the morphology of the Besterskraal North pipe as it is sub-economic and no mining has occurred. Samples from the Besterskraal North pipe were collected from the De Beers archives. The Kroonstad Cluster has been subjected to approximately 1750m of erosion post-emplacement, which has been calculated by the analysis of the crustal xenoliths with the pipe infill. The hypabyssal kimberlite from the three pipes shows a gradational evolution in magma compositions, indicated by the mineralogy and geochemistry. The Lace pipe is the least evolved and has characteristics more similar to Group I kimberlites. The Voorspoed and Besterskraal North kimberlite are intermediately and highly evolved respectively. The gradational evolution is marked by an increase in SiO2 and Na2O contents. Furthermore the occurrence of abundant primary diopside, aegirine, sanidine, K-richterite and leucite indicates evolution of the magma. The root zones of the pipes are characterised by globular segregationary transitional kimberlite, which is interpreted to be hypabyssal and not the result of pyroclastic welding/agglutination. The hypabyssal transitional kimberlite (HKt) is characterised by incipient globular segregationary textures only and the typical tuffisitic transitional kimberlite (TKt) end member (Hetman et al. 2004) is not observed. The HKt contact with the overlying volcaniclastic kimberlite (VK) infill is sharp and not gradational. The presence of HKt in the satellite blind pipe at Lace further indicates that the distinct kimberlite rock type must be forming sub-volcanically. The HKt is distinctly different at the Voorspoed and Lace pipes, which is likely a result of differing compositions of the late stage magmatic liquid. Microlitic clinopyroxene is only observed at the Lace HKt and is interpreted to form as a result of both crustal xenolith contamination and CO2 degassing. Furthermore the HKt is intimately associated with contact breccias in the sidewall. The root zones of the Kroonstad pipes are interpreted to form through the development of a sub-volcanic embryonic pipe. The volcaniclastic kimberlite (VK) infill of the Kroonstad pipes is not typical of South African tuffisitic Class 1 kimberlite pipes. The VK at Voorspoed is characterised by numerous horizontally layered massive volcaniclastic kimberlite (MVK) units, which are interpreted to have formed in a deep open vent through primary pyroclastic deposition. MVK is the dominant rock type infilling the Voorspoed pipe, however numerous other minor units occur. Normally graded units are interpreted to form through gravitational collapse of the tuff ring. MVK units rich in Karoo basalt and/or Karoo sandstone are interpreted to form through gravitational sidewall failure deep within an open vent. Magmaclasts are interpreted to form in the HKt during the development of an embryonic pipe and therefore the term autolith or nucleated autolith may be applied. Debate on the validity of the term nucleated autolith is beyond this study and therefore the term nucleated magmaclast is used to refer to spherical magmaclasts in the VK. The emplacement of the Kroonstad pipes is particularly complex and is not similar to typical Class 1 tuffisitic kimberlites. However the initial stage of pipe emplacement is similar to typical South African kimberlites and is interpreted to be through the development of an embryonic pipe as described by Clement (1982). The vent clearing eruption is interpreted to be from the bottom up through the exsolution of juvenile volatiles and the pipe shape is controlled by the depth of the eruption (+/-2km) (Skinner, 2008). The initial embryonic pipe development and explosive eruption is similar to other South African kimberlites, however the vent is cleared and left open, which is typical of Class 2 Prairies type and Class 3 Lac de Gras type pipes. The latter vent infilling processes are similar to Class 3 kimberlites from Lac de Gras and are dominated at the current level by primary pyroclastic deposition.
- Full Text:
- Date Issued: 2010
- Authors: Howarth, Geoffrey H
- Date: 2010
- Subjects: Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4961 , http://hdl.handle.net/10962/d1005573 , Geology -- South Africa -- Kroonstad , Kimberlite -- South Africa -- Kroonstad
- Description: The Cretaceous (133Ma) Kroonstad Group II Kimberlite Cluster is located approximately 200km south west of Johannesburg on the Kaapvaal Craton. The cluster is made up of six kimberlite pipes and numerous other intrusive dike/sill bodies. Three of the pipes are analysed in this study, which includes the: Voorspoed, Lace (Crown) and Besterskraal North pipes. These pipes were emplaced at surface into the Karoo Supergroup, which is comprised of older sedimentary rocks (300-185Ma) overlain by flood basalts (185Ma). At depth the pipes have intruded the Transvaal (2100-2600Ma) and Ventersdorp (2700Ma) Supergroups, which are comprised dominantly of carbonates and various volcanic units respectively. The pipes have typical morphology of South African pipes with circular to sub-circular plan views and steep 82o pipe margins. The Voorspoed pipe is 12ha in size and is characterised by the presence of a large block of Karoo basalt approximately 6ha in size at the current land surface. This large basalt block extends to a maximum of 300m below the current land surface. The main Lace pipe is 2ha is size with a smaller (<0.5ha) satellite pipe approximately 50m to the west. No information is available on the morphology of the Besterskraal North pipe as it is sub-economic and no mining has occurred. Samples from the Besterskraal North pipe were collected from the De Beers archives. The Kroonstad Cluster has been subjected to approximately 1750m of erosion post-emplacement, which has been calculated by the analysis of the crustal xenoliths with the pipe infill. The hypabyssal kimberlite from the three pipes shows a gradational evolution in magma compositions, indicated by the mineralogy and geochemistry. The Lace pipe is the least evolved and has characteristics more similar to Group I kimberlites. The Voorspoed and Besterskraal North kimberlite are intermediately and highly evolved respectively. The gradational evolution is marked by an increase in SiO2 and Na2O contents. Furthermore the occurrence of abundant primary diopside, aegirine, sanidine, K-richterite and leucite indicates evolution of the magma. The root zones of the pipes are characterised by globular segregationary transitional kimberlite, which is interpreted to be hypabyssal and not the result of pyroclastic welding/agglutination. The hypabyssal transitional kimberlite (HKt) is characterised by incipient globular segregationary textures only and the typical tuffisitic transitional kimberlite (TKt) end member (Hetman et al. 2004) is not observed. The HKt contact with the overlying volcaniclastic kimberlite (VK) infill is sharp and not gradational. The presence of HKt in the satellite blind pipe at Lace further indicates that the distinct kimberlite rock type must be forming sub-volcanically. The HKt is distinctly different at the Voorspoed and Lace pipes, which is likely a result of differing compositions of the late stage magmatic liquid. Microlitic clinopyroxene is only observed at the Lace HKt and is interpreted to form as a result of both crustal xenolith contamination and CO2 degassing. Furthermore the HKt is intimately associated with contact breccias in the sidewall. The root zones of the Kroonstad pipes are interpreted to form through the development of a sub-volcanic embryonic pipe. The volcaniclastic kimberlite (VK) infill of the Kroonstad pipes is not typical of South African tuffisitic Class 1 kimberlite pipes. The VK at Voorspoed is characterised by numerous horizontally layered massive volcaniclastic kimberlite (MVK) units, which are interpreted to have formed in a deep open vent through primary pyroclastic deposition. MVK is the dominant rock type infilling the Voorspoed pipe, however numerous other minor units occur. Normally graded units are interpreted to form through gravitational collapse of the tuff ring. MVK units rich in Karoo basalt and/or Karoo sandstone are interpreted to form through gravitational sidewall failure deep within an open vent. Magmaclasts are interpreted to form in the HKt during the development of an embryonic pipe and therefore the term autolith or nucleated autolith may be applied. Debate on the validity of the term nucleated autolith is beyond this study and therefore the term nucleated magmaclast is used to refer to spherical magmaclasts in the VK. The emplacement of the Kroonstad pipes is particularly complex and is not similar to typical Class 1 tuffisitic kimberlites. However the initial stage of pipe emplacement is similar to typical South African kimberlites and is interpreted to be through the development of an embryonic pipe as described by Clement (1982). The vent clearing eruption is interpreted to be from the bottom up through the exsolution of juvenile volatiles and the pipe shape is controlled by the depth of the eruption (+/-2km) (Skinner, 2008). The initial embryonic pipe development and explosive eruption is similar to other South African kimberlites, however the vent is cleared and left open, which is typical of Class 2 Prairies type and Class 3 Lac de Gras type pipes. The latter vent infilling processes are similar to Class 3 kimberlites from Lac de Gras and are dominated at the current level by primary pyroclastic deposition.
- Full Text:
- Date Issued: 2010
Investigations of the bioavailability/bioequivalence of topical corticosteroid formulations containing clobetasol propionate using the human skin blanching assay, tape stripping and microdialysis
- Authors: Au, Wai Ling
- Date: 2010
- Subjects: Adrenocortical hormones -- Bioavailability , Drugs -- Therapeutic equivalency , Adrenocortical hormones -- Effectiveness , Adrenocortical hormones -- Testing , Adrenocortical hormones -- Side effects , Transdermal medication
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3743 , http://hdl.handle.net/10962/d1003221 , Adrenocortical hormones -- Bioavailability , Drugs -- Therapeutic equivalency , Adrenocortical hormones -- Effectiveness , Adrenocortical hormones -- Testing , Adrenocortical hormones -- Side effects , Transdermal medication
- Description: Currently, clinical trials in patients are required by most regulatory authorities for the assessment of bioequivalence of topical products where the drug is not intended for systemic absorption. Hence there is a dire need for suitable methods for the assessment of bioavailability and bioequivalence of such products since clinical safety and efficacy studies are expensive, time-consuming and require very large numbers of patients. Except for topical corticosteroid products where the human skin blanching assay/vasoconstrictor assay has been approved by the US FDA for bioequivalence assessment of those products, no other method has been “officially” approved for use in those investigations. However, a few alternative methods such as tape stripping and microdialysis have been pursued and considered to have the potential for use in ioequivalence/bioavailability studies. The human skin blanching assay was used to assess the bioequivalence of commercially available topical products containing 0.05% clobetasol propionate. Both visual and chromameter data were obtained and a commercially available topical corticosteroid product, Dermovate® cream was used as both the “Test” and the “Reference” product. The results indicated that both visual and chromametric assessments were comparable to each other and that either could be used for the assessment of the bioequivalence of topical products containing clobetasol propionate. The screening procedure was optimized to identify potential “detectors” for inclusion in the bioequivalence studies. This resulted in fewer subjects being required in a bioequivalence pivotal study, still having the necessary power to confirm bioequivalence using the human skin blanching assay. Another objective of this research was to re-visit tape stripping and other possible alternative methods such as dermal microdialysis and to optimize these procedures for bioequivalence assessment of topical formulations where the drug is not intended for systemic absorption. In the past few decades, tape stripping has been used to investigate bioavailability/bioequivalence of various topical formulations. This technique involves the removal of the stratum corneum to assess drug penetration through the skin. A draft FDA guidance for tape stripping was initially published but was subsequently withdrawn due to high variability and poor reproducibility. This research project used an optimized tape stripping procedure to determine bioavailability and establish bioequivalence between three commercially available formulations containing 0.05 % m/m clobetasol propionate. Furthermore, tape stripping was validated by undertaking a study to assess the bioequivalence of a 0.05% topical cream formulation (Dermovate® cream) using the same cream as both the “Test” and “Reference” product, in which bioequivalence was confirmed. The findings highlight the potential of tape stripping as an alternative method for the assessment of bioequivalence of clobetasol propionate formulations and may possibly be extended for use in other topical products. Microdialysis is another useful technique that can assess the penetration of topically applied substances which diffuses through the stratum corneum and into the dermis. Microdialysis has previously been successfully used for in vivo bioavailability and bioequivalence assessments of topical formulations. However, the drugs which were under investigation were all hydrophilic in nature. A major problem with the use of microdialysis for the assessment of lipophilic substances is the binding/adherence of the substance to the membrane and other components of the microdialysis system. As a result, this necessitates the development of a microdialysis system which can be used to assess lipophilic drugs. Intralipid® 20% was investigated and successfully utilized as a perfusate to recover a lipophilic topical corticosteroid, clobetasol propionate, in microdialysis studies. Hence, the bioavailability of clobetasol propionate from an extemporaneous preparation was determined in healthy human volunteers using microdialysis. These findings indicate that in vivo microdialysis can be used to assess lipophilic drug penetration through the skin. A novel approach to investigate drug release from topical formulations containing 0.05% clobetasol propionate using in vitro microdialysis was also undertaken. The in vitro findings were found to be in agreement with the results obtained using tape stripping to assess bioequivalence of the same commercially available products, namely Dermovate® cream, Dovate® Cream and Dermovate® ointment. These results indicate the potential to correlate in vitro with in vivo data for bioequivalence assessment of such topical dosage forms.
- Full Text:
- Date Issued: 2010
- Authors: Au, Wai Ling
- Date: 2010
- Subjects: Adrenocortical hormones -- Bioavailability , Drugs -- Therapeutic equivalency , Adrenocortical hormones -- Effectiveness , Adrenocortical hormones -- Testing , Adrenocortical hormones -- Side effects , Transdermal medication
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3743 , http://hdl.handle.net/10962/d1003221 , Adrenocortical hormones -- Bioavailability , Drugs -- Therapeutic equivalency , Adrenocortical hormones -- Effectiveness , Adrenocortical hormones -- Testing , Adrenocortical hormones -- Side effects , Transdermal medication
- Description: Currently, clinical trials in patients are required by most regulatory authorities for the assessment of bioequivalence of topical products where the drug is not intended for systemic absorption. Hence there is a dire need for suitable methods for the assessment of bioavailability and bioequivalence of such products since clinical safety and efficacy studies are expensive, time-consuming and require very large numbers of patients. Except for topical corticosteroid products where the human skin blanching assay/vasoconstrictor assay has been approved by the US FDA for bioequivalence assessment of those products, no other method has been “officially” approved for use in those investigations. However, a few alternative methods such as tape stripping and microdialysis have been pursued and considered to have the potential for use in ioequivalence/bioavailability studies. The human skin blanching assay was used to assess the bioequivalence of commercially available topical products containing 0.05% clobetasol propionate. Both visual and chromameter data were obtained and a commercially available topical corticosteroid product, Dermovate® cream was used as both the “Test” and the “Reference” product. The results indicated that both visual and chromametric assessments were comparable to each other and that either could be used for the assessment of the bioequivalence of topical products containing clobetasol propionate. The screening procedure was optimized to identify potential “detectors” for inclusion in the bioequivalence studies. This resulted in fewer subjects being required in a bioequivalence pivotal study, still having the necessary power to confirm bioequivalence using the human skin blanching assay. Another objective of this research was to re-visit tape stripping and other possible alternative methods such as dermal microdialysis and to optimize these procedures for bioequivalence assessment of topical formulations where the drug is not intended for systemic absorption. In the past few decades, tape stripping has been used to investigate bioavailability/bioequivalence of various topical formulations. This technique involves the removal of the stratum corneum to assess drug penetration through the skin. A draft FDA guidance for tape stripping was initially published but was subsequently withdrawn due to high variability and poor reproducibility. This research project used an optimized tape stripping procedure to determine bioavailability and establish bioequivalence between three commercially available formulations containing 0.05 % m/m clobetasol propionate. Furthermore, tape stripping was validated by undertaking a study to assess the bioequivalence of a 0.05% topical cream formulation (Dermovate® cream) using the same cream as both the “Test” and “Reference” product, in which bioequivalence was confirmed. The findings highlight the potential of tape stripping as an alternative method for the assessment of bioequivalence of clobetasol propionate formulations and may possibly be extended for use in other topical products. Microdialysis is another useful technique that can assess the penetration of topically applied substances which diffuses through the stratum corneum and into the dermis. Microdialysis has previously been successfully used for in vivo bioavailability and bioequivalence assessments of topical formulations. However, the drugs which were under investigation were all hydrophilic in nature. A major problem with the use of microdialysis for the assessment of lipophilic substances is the binding/adherence of the substance to the membrane and other components of the microdialysis system. As a result, this necessitates the development of a microdialysis system which can be used to assess lipophilic drugs. Intralipid® 20% was investigated and successfully utilized as a perfusate to recover a lipophilic topical corticosteroid, clobetasol propionate, in microdialysis studies. Hence, the bioavailability of clobetasol propionate from an extemporaneous preparation was determined in healthy human volunteers using microdialysis. These findings indicate that in vivo microdialysis can be used to assess lipophilic drug penetration through the skin. A novel approach to investigate drug release from topical formulations containing 0.05% clobetasol propionate using in vitro microdialysis was also undertaken. The in vitro findings were found to be in agreement with the results obtained using tape stripping to assess bioequivalence of the same commercially available products, namely Dermovate® cream, Dovate® Cream and Dermovate® ointment. These results indicate the potential to correlate in vitro with in vivo data for bioequivalence assessment of such topical dosage forms.
- Full Text:
- Date Issued: 2010
The influence of Acacia Mearnsii invasion on soil properties in the Kouga Mountains, Eastern Cape, South Africa
- Van der Waal, Benjamin Wentsel
- Authors: Van der Waal, Benjamin Wentsel
- Date: 2010
- Subjects: Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4839 , http://hdl.handle.net/10962/d1005515 , Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Description: The invasion of Acacia mearnsii in the Kouga catchment, Eastern Cape, South Africa, has various negative impacts on the ecosystem. These impacts include: reduced species richness, increased water use, increased nutrients and increased N cycling rates. The native shrubby fynbos vegetation has adapted to the acidic nutrient poor soils and Mediterranean climate of the Kouga Mountains. Fynbos, however, is currently being out competed by the much taller Acacia mearnsii trees, due to their competitive nature and ability to fix nitrogen, thereby enriching the soil. The invaded sections of the valley bottoms and lower hill slopes are characterised by an almost complete monoculture of Acacia mearnsii, with very few fynbos species still present. The Department of Water and Environmental Affairs sponsored Working for Water programme started clearing Acacia mearnsii in 1996 in the Kouga Mountains. Cleared sites have remained bare for long periods, indicating that soil properties are not favourable for indigenous propagule re-establishment. The aim of this research was to assess how A. mearnsii invasion and clearing affect fynbos recovery through its impact on soils. This was done by characterising vegetation and soil properties on fynbos, infested and cleared slopes. Vegetation cover for various growth forms was determined and a species list was compiled for each plot. The slope angle, surface hardness, litter cover, bare ground cover and soil depth were measured in the field, whereas water repellency, particle size and the chemical composition were measured in the laboratory. Furthermore, the plant establishment capacity of soils from fynbos, infested and cleared slopes was calculated. This was done by germinating fynbos seeds and growing fynbos plants in soils from the various slopes. The effect that invasion and clearing has on soil erosion was quantified using erosion plots on fynbos, infested and cleared slopes. The invasion and clearing of Acacia mearnsii led to an increase in soil nutrients, especially nitrogen, phosphorus, potassium, carbon and manganese. Furthermore, soils became more acidic, with increased water repellency and reduced surface hardness. The vegetation changed to a tree-dominated structure, replacing the native species. Native plant germination was relatively unaffected by invasion and clearing, with an increase in germination just after clearing. Plant growth of a native grass, Themeda triandra, and herb, Helichrysum umbraculigerum, has increased on soils from cleared slopes. This study showed that soil movement increased on slopes which are invaded and cleared of Acacia mearnsii, with erosion rates doubling on invaded slopes
- Full Text:
- Date Issued: 2010
- Authors: Van der Waal, Benjamin Wentsel
- Date: 2010
- Subjects: Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4839 , http://hdl.handle.net/10962/d1005515 , Acacia mearnsii -- South Africa , Wattles (Plants) -- South Africa , Soil erosion -- South Africa -- Eastern Cape , Conservation of natural resources -- South Africa , Biological invasions -- South Africa -- Eastern Cape , Alien plants -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Biogeography -- South Africa -- Eastern Cape , Soil management -- South Africa -- Eastern Cape , Soil moisture -- South Africa -- Eastern Cape , Soils -- Sodium content -- South Africa -- Eastern Cape
- Description: The invasion of Acacia mearnsii in the Kouga catchment, Eastern Cape, South Africa, has various negative impacts on the ecosystem. These impacts include: reduced species richness, increased water use, increased nutrients and increased N cycling rates. The native shrubby fynbos vegetation has adapted to the acidic nutrient poor soils and Mediterranean climate of the Kouga Mountains. Fynbos, however, is currently being out competed by the much taller Acacia mearnsii trees, due to their competitive nature and ability to fix nitrogen, thereby enriching the soil. The invaded sections of the valley bottoms and lower hill slopes are characterised by an almost complete monoculture of Acacia mearnsii, with very few fynbos species still present. The Department of Water and Environmental Affairs sponsored Working for Water programme started clearing Acacia mearnsii in 1996 in the Kouga Mountains. Cleared sites have remained bare for long periods, indicating that soil properties are not favourable for indigenous propagule re-establishment. The aim of this research was to assess how A. mearnsii invasion and clearing affect fynbos recovery through its impact on soils. This was done by characterising vegetation and soil properties on fynbos, infested and cleared slopes. Vegetation cover for various growth forms was determined and a species list was compiled for each plot. The slope angle, surface hardness, litter cover, bare ground cover and soil depth were measured in the field, whereas water repellency, particle size and the chemical composition were measured in the laboratory. Furthermore, the plant establishment capacity of soils from fynbos, infested and cleared slopes was calculated. This was done by germinating fynbos seeds and growing fynbos plants in soils from the various slopes. The effect that invasion and clearing has on soil erosion was quantified using erosion plots on fynbos, infested and cleared slopes. The invasion and clearing of Acacia mearnsii led to an increase in soil nutrients, especially nitrogen, phosphorus, potassium, carbon and manganese. Furthermore, soils became more acidic, with increased water repellency and reduced surface hardness. The vegetation changed to a tree-dominated structure, replacing the native species. Native plant germination was relatively unaffected by invasion and clearing, with an increase in germination just after clearing. Plant growth of a native grass, Themeda triandra, and herb, Helichrysum umbraculigerum, has increased on soils from cleared slopes. This study showed that soil movement increased on slopes which are invaded and cleared of Acacia mearnsii, with erosion rates doubling on invaded slopes
- Full Text:
- Date Issued: 2010
Visual based finger interactions for mobile phones
- Authors: Kerr, Simon
- Date: 2010 , 2010-03-15
- Subjects: User interfaces (Computer systems) , Mobile communication systems -- Design and construction , Cell phones -- Software , Mobile communication systems -- Technological innovations , Information display systems , Cell phones -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4652 , http://hdl.handle.net/10962/d1006621 , User interfaces (Computer systems) , Mobile communication systems -- Design and construction , Cell phones -- Software , Mobile communication systems -- Technological innovations , Information display systems , Cell phones -- Technological innovations
- Description: Vision based technology such as motion detection has long been limited to the domain of powerful processor intensive systems such as desktop PCs and specialist hardware solutions. With the advent of much faster mobile phone processors and memory, a plethora of feature rich software and hardware is being deployed onto the mobile platform, most notably onto high powered devices called smart phones. Interaction interfaces such as touchscreens allow for improved usability but obscure the phone’s screen. Since the majority of smart phones are equipped with cameras, it has become feasible to combine their powerful processors, large memory capacity and the camera to support new ways of interacting with the phone which do not obscure the screen. However, it is not clear whether or not these processor intensive visual interactions can in fact be run at an acceptable speed on current mobile handsets or whether they will offer the user a better experience than the current number pad and direction keys present on the majority of mobile phones. A vision based finger interaction technique is proposed which uses the back of device camera to track the user’s finger. This allows the user to interact with the mobile phone with mouse based movements, gestures and steering based interactions. A simple colour thresholding algorithm was implemented in Java, Python and C++. Various benchmarks and tests conducted on a Nokia N95 smart phone revealed that on current hardware and with current programming environments only native C++ yields results plausible for real time interactions (a key requirement for vision based interactions). It is also shown that different lighting levels and background environments affects the accuracy of the system with background and finger contrast playing a large role. Finally a user study was conducted to ascertain the overall user’s satisfaction between keypad interactions and the finger interaction techniques concluding that the new finger interaction technique is well suited to steering based interactions and in time, mouse style movements. Simple navigation is better suited to the directional keypad.
- Full Text:
- Date Issued: 2010
- Authors: Kerr, Simon
- Date: 2010 , 2010-03-15
- Subjects: User interfaces (Computer systems) , Mobile communication systems -- Design and construction , Cell phones -- Software , Mobile communication systems -- Technological innovations , Information display systems , Cell phones -- Technological innovations
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4652 , http://hdl.handle.net/10962/d1006621 , User interfaces (Computer systems) , Mobile communication systems -- Design and construction , Cell phones -- Software , Mobile communication systems -- Technological innovations , Information display systems , Cell phones -- Technological innovations
- Description: Vision based technology such as motion detection has long been limited to the domain of powerful processor intensive systems such as desktop PCs and specialist hardware solutions. With the advent of much faster mobile phone processors and memory, a plethora of feature rich software and hardware is being deployed onto the mobile platform, most notably onto high powered devices called smart phones. Interaction interfaces such as touchscreens allow for improved usability but obscure the phone’s screen. Since the majority of smart phones are equipped with cameras, it has become feasible to combine their powerful processors, large memory capacity and the camera to support new ways of interacting with the phone which do not obscure the screen. However, it is not clear whether or not these processor intensive visual interactions can in fact be run at an acceptable speed on current mobile handsets or whether they will offer the user a better experience than the current number pad and direction keys present on the majority of mobile phones. A vision based finger interaction technique is proposed which uses the back of device camera to track the user’s finger. This allows the user to interact with the mobile phone with mouse based movements, gestures and steering based interactions. A simple colour thresholding algorithm was implemented in Java, Python and C++. Various benchmarks and tests conducted on a Nokia N95 smart phone revealed that on current hardware and with current programming environments only native C++ yields results plausible for real time interactions (a key requirement for vision based interactions). It is also shown that different lighting levels and background environments affects the accuracy of the system with background and finger contrast playing a large role. Finally a user study was conducted to ascertain the overall user’s satisfaction between keypad interactions and the finger interaction techniques concluding that the new finger interaction technique is well suited to steering based interactions and in time, mouse style movements. Simple navigation is better suited to the directional keypad.
- Full Text:
- Date Issued: 2010